Nightsister service droid

Those droids, the head of which somewhat ressembled the one of the EV-series supervisor droid, were used by the Nightsisters of Dathomir. Around 31 BBY, such droids were seen serving drinks to Queen Zalem and her fellow Sisters under a tent.

Behind the scenes
As the Nightsisters don't build droid themselves and didn't venture offworld at the time, those droids probably were castaways or shipwreck survivors.

Appearances

 * Star Wars: Republic 25: Infinity's End, Part 3