R4-M6
From Wookieepedia, the Star Wars wiki.
R4-M6 was an R4-series astromech droid socketed into Mace Windu's Eta-2 Actis-class interceptor. It was destroyed during the Battle of Coruscant, after Mace Windu collided with a fleet of vulture droids and droid tri-fighters, and was forced to jump out of the ship, abandoning it. R4-M6, like R4-P17 (and few other astromech droids owned by Jedi), was modified with the head of an R2-series astromech droid.
The droid was purple in colour, matching both Windu's starfighter and lightsaber blade colors, as well as those of one of his clone units.

