Best villain debut stories of the 1950s and 1960s

[Tzigone]

I've said before I think the first appearance of the Joker was a good story. The bronze age and later get some love. But what stories introducing recurring villains do you think shine in the '50s and '60s? Obviously, we have the new-at-the-time silver age heroes and their rogues galleries being introduced, but existing heroes got some new villains, too. I enjoy Heat Wave's first appearance, just for the budding bromance with Captain Cold.

[Electricmastro]

Deadshot from Batman #59 (June, 1950).

[LifeIsILL]

Any Justice League comics during that time, has all the first appearances of the classic villains.

My favorites would be Justice League of America #12 - Dr. Light, #29 - Crime Syndicate