Buce Quesillac is a character from Tyrian.
Buce was a member of the Hazudra, a lizard-like race. He was a close friend of Trent Hawkins, and like him he worked the terraformation of Tyrian. The two of them accidentally found about the Gravitium, which they initially dismissed as a random shiny ore, so Microsol captured Buce and attempted to brainwash him, but since his memory was holographic it failed. Microsol the decided to eliminate him, sending a hovering drone which killed him. Before dying Buce warns Trent about Microsol plans, kickstarting the game's events.
By the end of Episode 4, Trent comes to reflect on his lost friend and how he can't even remember his name due to all that happened. On Episode 5 the Collector will tell Trent that Buce was also a close friend of his.