R6-H5, nicknamed Arsix, was the astromech droid of Jedi MasterKit Fisto. He accompanied his Master on many missions for the Jedi Council. He was known for being tentative, often worrying about his master, and for having a dislike of strange situations.
When the clones tracked Grievous' starfighter incoming, they reported to CommanderFil. Shortly afterward, Grievous' IG-100 Magnaguards used a rocket launcher to destroy the shuttle with both clones inside it. When MagnaGuards surrounded the starfighter, Arsix received orders from Fisto to fly away, which he performed, shaking off a tenacious MagnaGuard who was clinging to the fighter's hull.
Arsix would then circle the area until Fisto ordered Arsix to meet him at the nearest landing platform. Once Fisto reached the platform, however, he was confronted by Grievous and his MagnaGuards. At that point in time, Arsix arrived in the starfighter, allowing Kit to board it and escape the battle. The two then returned to Coruscant, where Fisto reported his former Padawan's death to the Jedi Council.
Although his dome seems to be of an R2 unit and not the typical, slightly conical "flowerpot" shape of the R6, if R6-H5 is indeed an R6-series astromech droid, and not just an earlier model with an "R6" designation, his inclusion poses a continuity problem, as R6 units had not been created until the later stages of the Galactic Civil War.
Alternately, Pablo Hidalgo's revelation that droid names are fragments of longer designations could also provide an explanation for this apparent lack of continuity.[1]
Coincidentally enough, R6-H5 shares the "H5" with Kit Fisto's other droid, R4-H5.
R6-H5 appears in LEGO Star Wars III: The Clone Wars, in the Vassek scenario. Although he is not playable during this scenario, he can be found and unlocked, becoming a playable character. He has orange legs instead of brown.