Joker #7 (DC, 1975)

First 30-cent issue. Cover art by Ernie Chan (as Ernie Chua). "Luthor - You're Driving Me Sane!," script by Elliot S! Maggin, pencils by Irv Novick, inks by Frank McLaughlin; An experiment gone wrong switches Lex Luthor's and the Joker's personality; featuring the Mountebank Malefactors (villains), Southpaw (villain), Hal Jordan/Green Lantern (cameo), Larry Ingles (first appearance), and Joe Malone (first appearance).