Andross is the most often reoccurring enemy in the Star Fox games, and the final boss in Star Fox, Star Fox 64, and Star Fox Adventures.
Andross appears in several different forms throughout the Star Fox series. The most recognizable and famous form is his disembodied head with two floating hands. In the first game, he takes the form of a large metallic head covered in cube shapes. In Star Fox 64 and Star Fox Adventures, he has a brain that can act separately as well.
Before the first game, Andross works as one of the smartest and most valuable scientists for the planet Corneria. Although he has the best of intentions, his lust for power gets the best of him, and he accidentally unleashes a dangerous bio-weapon. As punishment, he is banished to the waste planet, Venom. He plots to dominate the entire Lylat System by building his own army but soon thereafter, Star Fox is sent to investigate. A traitor, Pigma Dengar, betrays the Star Fox team and delivers his friends into Andross' hands, resulting in Andross killing James McCloud, and proclaiming himself emperor of the entire Lylat System.
Determined to avenge his father by destroying Andross, and in turn save the Lylat system, a new Star Fox team is formed under Fox McCloud. Fox's first encounter with Andross is in his gigantic brain form on the planet of Venom. Fox defeats his brain form, causing Andross to self-destruct at the end of the battle. In his weak state, Andross takes refuge inside Krazoa Palace. The Sharp Claw dinosaur clan keeps him alive, but all attempts at a complete revival are for naught. Andross manipulates the dinosaur leader, General Scales, by making him collect various artifacts infused with the spirits of the Krazoa. Once he imprisons Krystal, a friend of Fox's, he is able to generate the energy he needs from the Krazoa Spirits and restore himself to full power. With his newfound power, Andross plans to obliterate the entire Lylat System for good, but Fox defeats him once again. This time, he has been completely destroyed. He reappears in Star Fox Command as a ghost, but never regains his full form.