StarCraft/Terran units

The production building for each unit is listed after the information about them.

SCV
The "Space Construction Vehicle" is the Terran's basic gatherer/builder unit. They cost 50 minerals. Typically, when mining minerals, you'll want two or three of these per mineral cluster, so that during the time when one SCV is returning its load, another SCV is working the patch. Often, you can need twenty per 'average' resource node (Around eight mineral patches). When collecting vespene gas, you'll wan't to assign SCVs until you see one waiting outside at all times.
 * Command Center

Marine
Marines are the base attack unit for the Terrans, and have the distinction of being the only initial unit with a ranged attack against both aerial and ground targets. While individually weak, you can put them in bunkers for protection - marine filled bunkers being repaired by SCVs make a very good defense if properly supported. Also, in Broodwar, train up squads of marines and mix in some medics (the famous M&M combination) - this works particularly well against Zerg. The stimpack upgrade is a must have, as with the advent of medics the increased fire rate (and hence attack damage) and speed is no longer offset by the loss of 10 HP.

Marines never go out of style: they can do damage to anything, have a ranged attack (so they get 'free hits' against melee units) and can be Stimmed and mixed with medics. They do a base 6 damage against all armour types (upgradeable to 6+3 = 9), and have zero base armor upgradeable to 3.
 * Barracks

Firebat
The Terran Firebat is the closest thing to a melee unit in the Terran arsenal. Like a Marine, a Firebat has to walk to get around, but in lieu of the (relatively) long ranged and minor damage rifle of a Marine, they carry short ranged flamethrowers that can fry anything they can get close to. They do splash damage in a line, which means that not only the individual unit the Firebat is attacking, but any of its buddies nearby take full damage from the Firebat's attack. The label says '16 damage', but if you take splash damage into account, when attacking multiple Zealots, Zerglings, or multiple anything else the Firebat can survive to get to, it's much more.

The catch is that the Firebat deals Concussion damage - so it only deals full damage to Small units (think Zealots, Zerglings, Marines...). It does reduced damage to medium units like Hydralisks, and a fraction to large units like Siege Tanks. Firebats require an Academy to be produced.
 * Barracks

Ghost
The Ghost is an infantry unit unlike the Marine and Firebat. Unlike his 'grunt' fellows, Ghosts are pitifully poor at dealing damage with normal attacks, doing a mere ten (base) concussive damage, with minimal effect against Medium and Large units. Instead, you should think of the Ghost more like a support unit or a spellcaster (If you're familiar with WarCraft). Against Protoss and Terran players, Lockdown is an indispensable ability: it renders a target mechanical unit totally motionless until Restored by a Medic or until the spell wears off. This works very well at stopping drops (lock down the dropship and halt the invasion while scrambling for defence) or neutralising heavy units for easy care or later disposal; think Siege Tanks, Battlecruisers or Carriers. Ghosts can also cloak for limited periods to get around unseen or attack with impunity (unless detected, at which point it's a good idea to run away real fast).

The most beloved ability of the Ghost, however, is the ability to guide a nuke down to ground zero. Provided you have a Nuke Silo and a prepped nuke, you can cloak your ghost and tell it to launch the nuke at a target for the greater of 500 or two-thirds damage to everything in the area. Seeing as even an Ultralisk only has 400HP and a battlecruiser has 500, a nuke can take out nearly anything - but it takes about 20 seconds to actually get there. Normally the ghost has to be within the damage radius and so dies after the nuke lands, unless the few second window between the end of targeting and detonation is used to tell them to run for it. The Ocular Implant upgrade from the Covert Ops will remedy this by allowing ghosts to target nukes from outside the damage radius.
 * Barracks

Medic
The Medic is a unit added in the Broodwar expansion pack, and is introduced to the Koprulu Sector by the UED's armies. The Medic will automatically heal damaged infantry (as well as SCVs, and Protoss infantry/Zerg units if they are allied with you). They increase the effectivness of infantry drastically. Medics require an Academy to be built.
 * Barracks
 * Brood War only unit.

Vulture
The Vulture is the base Factory unit, and like a Marine costs only Minerals, which is good for soaking up excess minerals that tend to build up in late game. Vultures with Ion Thrusters make truly incredible scouts and, if you're good, hit and run units - they even outrun Leg Enhanced zealots. Spider Mines are also useful for keeping an eye on things when used singly, and augment defense when used in minefields. Vultures do a base 20 Concussion damage against Ground units only, at 100% to Small, 50% to Medium and 25% to Large units.
 * Factory

Siege Tank
Once you research Siege Tech, the Siege Tank has two roles: as some seriously heavy support (but slow firing) in its mobile form, and as a serious artillery piece in Siege mode. In Tank mode, they do a base 30 Explosive damage (upgrade to 30+9 = 39): in Siege mode, they do a base 70 (upgradeable to 70+15 = 85). In Siege mode, they gain not only this more than double damage, but a collossal range boost, making them a good static defense as well as support artillery for a mobile army. However, they cannot attack air units, and deal Explosive damage - which means that Small units only take 50% and Medium units only take 75%.

However, while Siege tanks do very good damage, two points should be noted: there are many strategies for neutralizing them - Dark Swarm, Disruption Web and Lockdown for starters - and they fire slowly, doing splash damage to even friendly units. If you rely on large numbers of tanks for defense only, you can easily blow up more of your own tanks than the enemy.
 * Factory

Goliath
The Goliath is your friend. It has not only a respectable 12 base damage against all ground units, but more importantly, a long ranged (once you research Charon Boosters) anti air attack on par with the missile turret. An upgraded Goliath will do 20 + 12 explosive damage to anything in the air - and unlike the faster firing Missile Turrets, Goliaths are mobile. Mix in some goliaths with your attack forces so you have some anti air support superior to what Marines alone can provide, and watch the air units crash and burn.
 * Factory

Dropship
The dropship is what you use when your units need to take the high road over obstacles, blockades or water (island maps), or just when you want to strategically drop units in superior positions or vulnerabilities in enemy defenses. There's nothing quite like the satisfaction of dropping a few tanks and goliaths onto a cliff and watching the tanks blast the living daylights of everything down below, while the Goliaths provide air cover.
 * Starport

Wraith
The Wraith is a fast airborne combat vehicle. It is capable of attacking both air and ground units. It also has the ability to cloak. Typically they're used to pester outlying enemy installations or fortifications. However, if the enemy brings a "detector" the Wraiths will be revealed, which makes them vulnerable but no less effective at screwing with the enemy.
 * Starport

Valkyrie
(Brood Wars Only) The Valkyrie is an air-to-air unit. It's not all that popular but has some use. Typically you build them when your expecting a large fleet of air units coming your way, particularly Mutalisks and Wraiths Valkyries do splash damage and can quickly anihillate groups of air units.
 * Starport
 * Brood War only unit.

Battle Cruiser
The Battlecruiser is the Terrans most powerful air unit. BC's are sometimes used to harass the enemy with their long range Yamato Cannon. They are excellect for killing Terran missle turrets to enable penetration by cloaked units.
 * Starport

Science Vessel
The Science Vessel is the Terrans' other spellcasting unit. It has a few spells that are useful. Defensive Shield can be used to bolster a units hp up (it adds ~200 temporary hp). Irradiate damages living organisms, so it can be cast on Zerg swarms to weaken a cluster of them (try casting on a group of bunched up guardians, and watch them suffer, or cast it on your seige tank. The tank won't take damage, but Zerglings that are attacking your tank will.) The other spell, EMP, takes away all the energy (spellcasting points) from units, and all the Protoss shields. A well cast EMP shockwave essentially halves the Protoss units hitpoints, it'll also force Wraiths and Ghosts to decloak.
 * Starport

Zealot
A ground unit, a Zealot channels his enormous psychic powers into creating a plasma shield and energy blades for offensive and defensive purposes. The Zealot is excellent at hand-to-hand combat, and can take a lot of pounding. They can't attack air targets though.
 * Gateway

Dragoon
A Zealot, after becoming mortally wounded, can volunteer to have its brain placed inside a robotic exoskeleton, and becomes a Dragoon. The Dragoon shoots bolts of antimatter at ground and air targets, and moves moderately quickly.
 * Gateway

Scout
A light aircraft, the Scout has twin guns under its wings and a pair of missile launchers. Mostly useful against heavy air units.
 * Stargate

Carrier
Heavily armored flying machines, they manufacture robotic Interceptors to attack targets. Carriers can hold 8 Interceptors, and are very nasty if used in numbers.
 * Stargate

Interceptors
Small robotic fighters with limited range which are spawned from Carriers. They fly randomly and then all rush the target at once and shoot it and disperse. Can easily confuse an enemy as to which one to hit, and seeing tons of these things flying around can have a noticable phsycological impact on a human opponent.
 * 

Reaver
The Protoss equivalent of a Seige Tank, the Reaver shoots robots called Scarabs which race across the field and explode. Downside: They move excruciatingly slowly and can't attack air targets, and also require each scarab to be purchased for 15 minerals and a short build time.
 * Robotics Facility

Shuttle
As it's name implies, the Shuttle ferries other units by air around the map. It has no real other purpose.
 * Robotics Facility

Observer
The Observer is a permanently cloaked air unit which can do nothing but move around and spy on the map being weaponless and permanently cloaked. These are very useful for putting in unclaimed resource areas or other strategic areas (Mountain passes, lookout point, enemy perimeters) to keep tabs on the board.
 * Robotics Facility

Arbiter
Spell-caster, an Arbiter casts a cloaking field on groups of units underneath it. It has Stasis Field, and Recall for spells. You can't cloak an Arbiter with another one, unfortunately.
 * Stargate

Corsair
Attacks only air targets w/small neutron pulses. Can also deploy Disruption Webs, which prevent ground units under the web from attacking. Used mostly for disabling enemy tanks and defensive structures, (with D-web) and hunting Zerg Overlords. Medium unit.
 * Stargate
 * Brood War only unit.

High Templar
Spell-caster: doesn't attack directly, but can use the powerful spell Psionic Storm, as well as hallucinations. 2 can be merged into an Archon.
 * Gateway

High Archon
The High Archon is a psionic entity created via Archon Meld using two High Templar. It is a hovering (does not activate spider mines) melee attack unit against both ground and air based enemies. It possesses 350 shields and 10 life points. Its main attack has a fast attack rate and deals 30 points of damage, making it the third strongest Protoss unit in the game, after Reavers and Dark Templar.

If you click on a High Archon enough and it will say "power overwhelming", a StarCraft cheat code.

Advantages:
 * High Archon is basically shields only, so it only takes 9 damage from the Zerg Plague spell.
 * No matter how badly the High Archon is hit, it can and will regenerate all of its shields, given the time.
 * Creation of a High Archon in the midst of a battle from two High Templar that have been exhausted of their energy allows players to get the most out of their High Templar. Beware that Archon Meld takes a while, during which the High Archon is vulnerable.
 * Unlike the Dragoon and Scout ATA attacks, the High Archon's Psionic Blast is not Explosive, meaning that it deals full damage against small air based units like the Mutalisk.
 * The High Archon's splash damage makes it a great weapon to use against stacked enemy air units.

Disadvantages:
 * A single hit from the Terran EMP Shockwave can completely remove all of a High Archon's shielding, at which point it has no chance of surviving unless it can be evacuated to safe territory immediately (With 10 hit points, a couple of SCVs could conceveably take it out).
 * A fast unit such as the Vulture and Corsair can attack the High Archon with impunity, since the High Archon attacks using melee.
 * Shields do not provide as much protection as standard armor and so the High Archon will still take full damage from Concussion type attacks.


 * High Arcons are created by merging two High Templars. No buildings are required.

Dark Templar
Assassins, they are endowed with a permanent cloak. They have enormous attack damage, yet little shields/HP. They can merge into a Dark Archon in Brood Wars.
 * Gateway

Dark Archon
Created from two Dark Templar, is a spell-caster, and can mind control other units.
 * Created from merging two Dark Templars, similar to High Templars.
 * Brood War only unit; merging two Dark Templars in the original game creats a normal High Archon.

Zerg
Note that except for the four units listed below, ALL Zerg units are created from eggs at a Hatchery.

Drone
The worker unit, like the SCV. Can burrow, but just kill them like you would an SCV.

Zerglings
Zerlings are cheap and overwhelming to enemies. They're so good for flooding players they've given their name to a general battlefield tactic: the Zergling rush. Designed to be melee units, and can be bred two at a shot from a larva. Used in enormous numbers, they can damn near wipe out everything as long as they aren't killed first. 'Lings' are a common nickname for these, and 'cracklings' refer to their most upgraded form (+speed, +attack speed, +3 attack and +3 defense). Most obvious downside, any aircraft can kill them easily, as they can't attack air targets. Also, marines in bunkers, a lot of zealots, or more zerglings can be very efficient at wiping out hordes of them.

They can be easily ripped apart using firebats.
 * Common Strategies --- 4 or 6 ling rush in the first 1 or 2 minutes of a game, Muta-ling rush within the first 5 minutes of the game, and commonly used with Defilers and Ultralisks. These stronger units, if used correctly, will act as a sponge and allow these Zerglings enough time to cause some damage.

Hydralisks
These things spit hyper-velocity, super-dense darts at you, ripping you to pieces. Used in great numbers, they can annihilate everything (both ground and air). These are general "mobbers": they can handle everything as they are not specialists in any kind of way. Be wary of the general mob-killers such as Tanks, Reavers, and High Templar.

Mutalisk
A 'small' flying creature, the Mutalisk shoots a worm at you that ricochets and hits other targets. They do fairly low damage, but are fast, and cheap for an air unit. Paired up with Zerglings they can counter nearly all enemies.

Ultralisk
Very tough and moderately damaging ground units. Most commonly used to absorb damage while other units deal it, but can be fairly effective by themselves as well.

Guardian
The Mutalisk can mutate into the armored, long-range Guardian. The Guardian can't atack air targets, and can only shoot at the ground, but is incredibly effective against ground units.
 * Guardians are created in mutation from Mutalisk after researching them.

Scourge
Suicide units, they fly into air units and explode, dealing massive damage. A few of these can easily trash a battlecruiser or fleet of lesser ships.

Defiler
Spell-caster; casts plague, dark swarm. Luckily for their enemies they don't have any conventional weapons, so they're easy to kill once found with detectors. Plauge will gradually drain the HP of units or buildings that were in the area of effect by up to 500, but will not reduce it below 1 (IE. Wont kill them outright). Note that units under a Dark Swarm are immune to ranged attacks, a very powerful effect, but one that can cut both ways against an opponent with melee units of their own Note: Archons and Tanks will still damage units because of splash damage. However, the initial 30 or 70 attack that hits the target will be nullified to 0.

Queen
A flying spell-caster. Nasty, but easy to defend against. Ensnare, Spawn Broodling, Infest Command Center, and Parasite for spells. Spawn Broodling is an instant kill for all non-robotic ground units. (Dark) Archons and Reavers are the only "robots" in the game.

Infested Terran
Once a Queen has infested a sufficiently damaged Terran Command Center, the people inside are enaslaved and genetically modified into explosive suicide ground units. They run up to their target(s) and explode, causing horrendous damage in game statistics. If you're a Terran playing against a strong Zerg opponent, guard your command centers, or blow them up when they're hopelessly under attack.
 * Created at the infested Command Center like SCVs.

Devourer
Evolves from Mutalisk and is the slowest attacking unit in the game. Launches acid at other air units that deteriorates their armor, giving up to -9 armor.
 * It's not the Devourer itself that is so powerful, but the acid that comes with it that kills. Never send Devourers on their own, they will be ripped to shreads even by the weakest of air units. Mutalisks and Hydralisks pair well with these, as every time a Devourer attacks, Mutalisks will do more damage with their own attacks.
 * Created in mutation from Mutalisk after researching it.
 * Brood War only unit

Lurker
Lurkers can only attack when burrowed, but have a straight-line area effect attack, making them very powerful against bunched-up units, particularly low HP units like Marines.
 * Created in mutation from Hydralisk after researching it.
 * Brood War only unit.