R8B7

R8-B7 is Mace Windu's astromech droid for a brief period during the Clone Wars.

Biography
The droid co-piloted Windu's Delta-7B Aethersprite-class light interceptor to Vanqor, where Windu and Anakin Skywalker were searching for survivors at the crash site of the Endurance after its crash landing there.

While scouting out the terrain surrounding the wreckage along with R2-D2, R8-B7 was cornered and attacked by two of the planet's native gundarks. R2-D2 attempted to save the hapless R8-B7 but was knocked out of the fray. Following R8-B7's destruction, R2-D2 flew Windu's Delta-7B offworld to inform the Jedi Council of Skywalker and Windu's situation on Vanqor.

Behind the scenes
Because R8-B7 is named as an R8-series astromech droid, which were first manufactured in the late stages of the Galactic Civil War, this sets up a canonical ambiguity identical to that raised by the units R7-A7 and R7-D4.

Alternately, Pablo Hidalgo's revelation that droid names are fragments of longer designations could also provide an explanation for this apparent lack of continuity.