Oopsla! is a science fiction fanzine by Gregg Calkins.
Contributors included Ron Bennett (Ploy), John Berry (Pot Pourri), Robert Bloch, Vernon L. McCain (Wastebasket), with his column, "The Mark Of McCain", Wilson "Bob" Tucker (Le Zombie), Harry Warner, Jr. (Horizons), and Walt Willis (Hyphen), with his column, "The Harp That Once Or Twice".
The article "Bah! Humbug!" by Robert Bloch was included in the fan anthology The Best of Fandom 1958.