Real world article
(written from a production point of view)
Referenced in the final draft script of the Star Trek: The Original Series episode "Miri", a lion tamer is a person who professionally tames and trains lions, especially for entertainment in a circus.
In the aforementioned teleplay, a generic lion tamer was mentioned, as the script likened James T. Kirk confronting a gang of Onlies in a classroom to a lion tamer surrounded by "too many" lions in a cage.