William Joseph "Billy Blaze" Blazkowicz II, a.k.a. Commander Keen (or sometimes just Keen) is the hero in a series of games with the same name. Even though Keen is only eight years old, he's highly intelligent for his age; it's said that he has a IQ of 314. Commander Keen usually wears a purple t-shirt, jeans, and an American football helmet painted in Green Bay Packers colors that he borrowed from his brother.
Keen is the grandson of William Joseph "B.J." Blazkowicz, the protagonist of Wolfenstein 3D, another id Software release. His parents are Arthur Kenneth Blaze, a Milwaukee talk show personality, and Susan Elizabeth McMichaels. Arthur changed his surname from Blazkowicz to Blaze to make it sound more showbiz-like. Keen also has one older brother and one possibly younger sister, but their names are unknown.
Keen appears as a character that must be killed in a secret level of Doom 2.