It's long been known that Bat-villainess Poison Ivy was created in the comics in order to give Batman more female villains on the '66 TV series and yet she never appeared on the show. She barely even appeared in the comics for years outside of her initial stories and the syndicated newspaper strip. However, did you know that, in fact, Poison Ivy DID appear on the TV series, albeit as a very different character--Lesley Gore's Pussycat! Take a look at these memos from the network censor clearly indicating the name change from "Poison Ivy" to "Pussycat!"
Also found a piece indicating that Pussycat was supposed to give Robin his first kiss in the episode only to have the Producer, Howie Horwitz, nix the idea, much to Burt Ward's "ranting and raving" disappointment. Lesley said she was glad it was canceled (because she was gay?) but that she had a feeling it wouldn't REALLY have been his first kiss anyway (a reference to Ward's self-proclaimed sexual exploits behind the scenes?).