Petronius, a Roman author and satirist known formally as Gaius Petronius Arbiter

Arbitration, in law a method of dispute resolution

Arbiter (Halo), a character in the Halo video game series

Referee in sporting matches

Arbiter (electronics), in computing and electronics a circuitry component

Wavefront arbiter, a commercial memory arbiter optimized for high-speed operation

HMS Arbiter (D31), an escort aircraft carrier in the Royal Navy of the United Kingdom

International Arbiter, in chess a title conferred by FIDE to match referees

Arbiter-class starships, Protoss support vessels in the StarCraft science-fiction series.