Beast is one of the most common creature types in Magic. They appear mostly in green, with red as a common second color. Beasts are usually efficient midsize-to-large creatures, the best and greatest being Krosan Beast, but as a person of taste, you already knew that without reading this description.
Wirewood Savage draws a card whenever a Beast enters, making typal support. Contested Cliffs turns any Beast into repeatable removal by having it fight an opponent's creature. And famously, Craterhoof Behemoth can end the game in one swing once your board is wide enough.