If you thought it odd that we titled it "a Supergirl" instead of just "Supergirl", there's a reason for that. This issue is 9 months before the first appearance of the real Supergirl Kara Zor-El (Action Comics #252). The Supergirl in this issue is the result of Jimmy Olsen drinking a potion of three wishes, and using his first wish to create someone just like Superman who he can be more than just pals with. So this is indeed the first appearance of a character called Supergirl - it's just not the Supergirl. Cover by Curt Swan and Stan Kaye