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. Ursula is at home in the hot and dry Arid Desert climate.

Alexander
Alexander is the Terrennial of wind. You unlock him after defeating and purifying the Poes. His climate is cold, windy Humid Continental

Tove
Tove is the Terrennial of earth. You unlock him after defeating and purifying the Poes. He is at home in the Tropical Rainforest climate.

Ezra
Ezra is the Terrennial of ice. You unlock her after defeating and purifying Stoker. Her climate is the Frigid Arctic.