Alcimus was a high priest in Jerusalem in the 2nd century BC.
Alcimus may also refer to:
- Alcimus (fly), a genus of robber flies in the family Asilidae
- Alcimus (mythology), several figures in Greek mythology
- Alcimus (rhetorician), 3rd-century BC Greek rhetorician
- Alcimus Alethius, 4th-century Latin poet
- Avitus of Vienne, 6th-century bishop, also known as Saint Alcimus Ecdicius Avitus