Lunar Knights/Terrennials

Toasty
Toasty is the Terrennial of Sol, or sunlight.

Nero
Nero is the Terrennial of darkness.

Ursula
Ursula is the Terrennial of fire. You unlock him after you defeat and purify Rymer.

Alexander
Alexander is the Terrennial of wind.

Tove
Tove is the Terrennial of earth.

Ezra
Ezra is the Terrennial of ice. You unlock her after defeating and purifying Stoker.