When and where did the character of Mr. Freeze first appear in DC Comics?

The character who would become Mr. Freeze first appeared as 'Mr. Zero' in *Batman #121* (February 1959). He was a generic, cold-themed villain. He was later renamed 'Mr. Freeze' for the *Batman* television series of the 1960s, a name that was then adopted by the comics. However, his modern, sympathetic, and tragic origin story (as Victor Fries seeking to cure his wife Nora) was not established until the *Batman: The Animated Series* episode 'Heart of Ice' in 1992, subsequently integrated into the comic book canon.