In the reign of Caligula a slave named Androcles was set free at Rome in rather unusual circumstances. The story is told by A. Gellius (5.14). Having been sentenced to death by exposure to wild animals in the amphitheatre (a standard penalty for slaves guilty of capital offences), Androcles was one of a group of prisoners who appeared in the Circus Maximus on a day when the emperor himself happened to be in the audience. Expectations of a fine spectacle were high owing to the exceptional size and ferocity of one of the waiting lions, but instead of a bloody battle between man and beast, the crowd witnessed an altogether different sight: for the ferocious lion recognised Androcles as an old companion and to the amazement of all turned the slave's terror to joy by refusing to attack him. By popular demand Androcles was delivered from his punishment, set free and given custody of the lion.

When summoned to account for the animal's extraordinary behaviour, Androcles informed the emperor that in Africa years before he had once removed a huge splinter from the lion's paw, having unwittingly taken refuge in the lion's lair while running away from his master, who was then serving as the province's governor. The grateful lion had subsequently shared his quarters with Androcles and helped him to survive, but Androcles was eventually captured by Roman troops and restored to his owner (now back in Rome), who had him condemned to death for having run away.