Unknown Artist - "It Could Have Been Me" (1965)

Juliet Prowse and Sal Mineo dancing to the dynamite "It Could Have Been Me", in a scene from the notoriously sordid movie shocker Who Killed Teddy Bear.

I don't know who that is singing. Bob Gaudio of the Four Seasons may have co-written it (the opening credits imply this) with New York session vet Al Kasha -- who may be singing. But really your guess is as good as mine.