Eppillus (Celtic: "little horse") was the name of a Roman client king of the Atrebates tribe of the British Iron Age.
He appears to have ruled part of the territory that had previously been held by Commius, the Gaulish former ally of Julius Caesar who fled to Britain following the uprising of Vercingetorix, or possibly of his son.
[1] After Commius's death in about 20 BC, based on numismatic evidence, Eppillus seems to have ruled jointly with another ruler named Tincomarus.
[1] Eppillus's capital was Noviomagus Reginorum (Chichester) in the south of the kingdom, while Tincomarus ruled from Calleva Atrebatum (Silchester) in the north.
Eppillus became ruler of the whole territory a little before 7 AD, and Tincomarus appears as a supplicant to the Emperor Augustus in his Res Gestae, so he would seem to have been driven out in some sort of domestic intrigue.