Goombas
- Goomba
Denizens of the Mushroom Kingdom who have turned traitor and now serve the Koopa Troop. They can be flattened with a single stomp or defeated in all sorts of ways.
- Paragoomba
A goomba with wings, essentially. Stomping it grounds the goomba, which can then be dealt with as above.
- Micro Goomba
Tiny gommbas that can appear in a few worlds. These can't hurt you, but if they get onto you, they can crawl all over you and slow you down. If that happens, Spin Jump to shake them off.
- Grand Goomba
A large goomba twice the normal size. Normally seen in the World 1 enemy ambush. Stomping one causes it to split into two regular-sized goombas.
- Mega Goomba
As if Grand Goombas were big enough, these huge critters are four times the normal size and split into two grand goombas when stomped.
Koopa Troopas
- Green Koopa Troopa
The rank and file of the Koopa Troop, these turtles will walk the levels, turning when they hit a wall or other enemy but walking off ledges. Stomping them once causes them to retreat into their shells, which you can pick up and/or kick along the ground. A koopa shell can defeat other enemies as they slide along the ground but can also hit you, too!
- Red Koopa Troopa
Unlike their green counterparts, Red Koopa Troopas patrol smaller areas because they turn around at a ledge. Otherwise, they act the same.
- Green Koopa Paratroopa
- Red Koopa Paratroopa
Koopa Troopas with wings that let them fly. They can be seen flying either in back-and-forth patrol paths or simply moving along in a certain direction. Stomp them once and they'll be grounded, reverting to the walking patterns dictated by their shells.
Piranha Plants
- Piranha Plant
Carnivorous plants that tend to live in pipes. Many of them can sense when Mario is nearby and won't come out if he's too close. Be careful otherwise.
- Venus Fire Trap
These more-aggressive plants have the ability to spit fireballs in your direction when they come out.
- Super Piranha Plant
- Super Venus Fire Trap
Giant versions of the above that otherwise act the same.
- Stalking Piranha Plant
- River Piranha Plant
- Muncher
Small but unstoppable, these plants can make going difficult. You can't remove them without help from a P-Switch; you usually have to find ways around them. Treat them like spikes.
Hammer Bros.
- Hammer Bro
These elite members of the Koopa Troop toss a never-ending supply of hammers your way and have a tendency to jump up and down if there are platforms in the area. They can be stomped and dealt with otherwise but the constant barrage makes approaching them difficult.
- Boomerang Bro
Hammer's relatives from down under, instead of hammers, these green Bros toss boomerangs. They're slower and more predictable than the hammers, but remember: boomerangs come back!
- Fire Bro
From the hot desert, these red Bros lived on Fire Flowers and gained the ability to spit fireballs at you. These act just like Mario's fireballs when launched.
- Sledge Bro
This Giant Bro tosses hammers like the regular Bro but is so huge that when he leap, he causes earthquakes upon landing, stunning you if you're on the ground.
- Ice Bro
The newest Bros from the frozen reaches where Ice Flowers are their preferred diet, meaning they attack by spitting ice balls. Just like with your ice balls, not only will they hurt you, but they'll freeze you in ice momentarily.
Beetles
- Spiny
The annoying spiked-shell critters that are constantly thrown by Lakitu. Their spikes mean you can't stomp them, but they will react to just about anything else.
- Buzzy Beetle
These critters may wander a level in the same way as a Green Koopa Troopa. You can stomp, carry, and kick them like Koopa Troopas, but their special shells mean they don't react to fireballs, but they will react to other things. Also remember that Buzzies can sometimes be seen crawling on ceilings. If you see one like this, they will drop from the ceiling and spin towards you when you get close.
- Spike Top
The worst of both worlds, a Spike Top can neither be stomped (because of its namesake spike) nor fried (because it has the same type of fireproof shell). Also, they are very skilled at crawling along walls and ceilings, tuning the corners quite easily so as to keep going. But there are ways to beat them (shells, Starman, knocking around the block they're walking along, etc.).
- Para-Beetle
Unlike other winged creatures, Para-Beetles are virtually invincible. Indeed, you usually don't want to defeat these creatures because they tend to appear in wide-open areas; you'll need to hop on their backs and hitch a ride in order to get across the vast empty expanses they cross.
- Heavy Para-Beetle
These larger versions will appear in only one course. They have difficulty enough as it is flying so the moment you land on it, Heavy Para-Beetles will start to sink from the sky. Be sure to find another place to land before it takes you with it.
Cheep-Cheeps
- Cheep-Cheep
These fishy foes are dangerous, despite their appearance. They dwell underwater, and often appear in massive shoals of 5-10. The fire flower works best - stay slightly above them and fire!
- Mega Cheep-Cheep
A, uh, big Cheep-Cheep. Less prone to hanging out in shoals, but if frozen, their large bodies mean that they can easily shatter on nearby obstacles - use this to your advantage!
- Deep-Cheep
Green Cheep-Cheeps that are a little more cantankerous than their red cousins, Deep-Cheeps will swim towards Mario as long as they are in front of him. The method for defeating Cheep-Cheeps above works well on them, too.
- Mega Deep-Cheep
A, uh, big Deep Cheep. That is all.
- Spiny Cheep-Cheep
These fellows take the whole 'chase Mario' thing to a whole new level - they just won't give up the chase! Even for their small size, Spiny Cheep-Cheeps can be deadly, and often appear close together in groups of around 3 or 4.
- Eep-Cheep
- Porcu-Puffer
- Cheep-Chomp
- Fishbone
Other Water Enemies
- Blooper
- Blooper Nanny
- Baby Blooper
- Urchin
- Mega Urchin
- Huckit Crab
- Clampy
- Bulber
- Jellybeam
Artillery Enemies
- Bullet Bill
- Banzai Bill
- Missile Bill
- Missile Banzai Bill
- King Bill
- Bob-omb
- Para-bomb
- Chain Chomp
- Fire Chomp
- Amp
- Rocky Wrench
- Mecha-Koopa
Ghosts
- Boo
- Big Boo
- Circling Boo Buddies
- Broozer
- Scaredy Rat
- Ghost Vase
- Crowber
Fire Enemies
- Podoboo
- Fire Snake
Others
- Monty Mole
- Swooper
- Pokey
- Bramball
- Spike
- Stone Spike
- Wiggler
- Mega Wiggler
- Cooligan
- Fuzzy
- Mega Fuzzy
- Foo
Object/Obstacles
- Cannon
- Cannonball
- Giant Cannonball
- Rocket Engine
- Spiked Ball
- Giant Spiked Ball
- Spiked Pillar
- Giant Spiked Pillar
- Ball 'n' Chain
- Firebar
Fortress/Castle Enemies
- Dry Bones
The re-animated remains of long-dead Koopas. They are fireproof, and if you stomp one, it only stays down for a few seconds before reassembling itself and starting up again. You can smash them for good, however, if you freeze them first.
- Super Dry Bones
A larger Dry Bones that requires Ground Pounding to break apart. They will react to freezing, but they can break out much more quickly.
- Thwomp
Huge stones that sense intruders and will drop themselves to the ground if you get too close. Try to lure them into dropping then getting out of the way. Then you can cross as they try to get themselves back up to dropping height again.
- Super Thwomp
Pretty much as one can picture it: a much-larger piece of rock that otherwise acts the same way. Still, being so big, getting out of its way can be rather tricky, especially since it's so heavy that it can smash through bricks, meaning they can't be relied upon for protection. But since it's so big you may find crevices in the floor you can hide in to avoid its crushing bulk.
Bosses
- Larry Koopa
- Roy Koopa
- Lemmy Koopa
- Wendy O. Koopa
- Iggy Koopa
- Morton Koopa Jr.
- Ludwig von Koopa
- Kamek
- Bowser Jr.
- Bowser
- Giant Bowser