Commander Keen, Billy Blaze by his real name (full name William Joseph Blazkowicz II), is an eight-year-old child genius with an IQ of 314 (a reference to Pi and one point less than his nemesis Mortimer McMire). With his extreme intelligence, Keen has been able to make several inventions that he uses to aid himself in his adventures. His inventions are also an important part in each episode's story. In his spare time, Keen defends the Universe and maintains the order of galactic laws. He travels intergalactic distances in his space ship, the Bean-with-Bacon Megarocket, which he designed and built out of typical house-hold materials. When at home, he spends time in his Club House, inventing things and scanning space with his Photachyon Transceiver, which is also an invention of his.
Keen wears blue jeans, red converse, a purple T-shirt, and his older brother's yellow Green Bay Packers football helmet. He has brown hair and is of very pale complexion. He has the ability to jump quite high, and can reach even higher since he discovered the pogo stick on his trip to Mars. The pogo has since become his trademark move. Moreover, he has the ability to stay unharmed after jumping from any height (unless the surface is dangerous, e.g. fire, spikes, alien monsters etc.), and always lands on his feet. Keen has a pet Yorp called Spot. He adopted it when he was first on Mars. He has a mother and father, and an older brother and a younger sister. The age of his siblings is actually never revealed, however.
On his trips Keen, while knowing much already, also learns new things, such as Omnispeak that was taught to him by the Vorticons, and the Standard Galactic Alphabet in Vorticon VI. Besides Earth, some of the planets Keen has visited on his travels include Mars, Vorticon VI, Gnosticus IV, Korath III and Fribbulus Xax. Keen is a friend of several alien races, including the Vorticons and the Gnosticenes (who still owe Keen a favour).
Keen's appearance changes with each new adventure:
Invasion of the Vorticons
Classic Keen, from the first trilogy.
Modern Keen, in his pyjamas.
Modern Keen, from the second trilogy.
Game Boy Keen
Game Boy version of Commander Keen.
- Billy Blaze appears as a marine guy action figure named "Keenguy" in the Doom 2016 reboot. Selecting him will view the BFG 9000 model.
- After the Wolfenstein RPG level 'Compound', B.J. Blazkowics is given health packs by a man who introduces himself as Commander Keen.