He appeared in many other films too, of course, but starring roles were few and far between for him. Perhaps his second finest moment was in a disturbing psychological thriller from 1965 called WHO KILLED TEDDY BEAR? It's not often seen or discussed, and to be frank, it has real flaws. It is directed by stage and TV journeyman Joseph Cates and written by Arnold Drake, probably otherwise best known as a comic-book writer - he created the Guardians Of The Galaxy.
Mineo, who is excellent, stars as a young man employed as a nightclub waiter, tormented by his own sexual hangups, who falls for the club's new DJ, glamorous Juliet Prowse, and is ripped apart by his inner conflicts, which boil over into their lives. As you can probably guess, it does not end well for anyone.
The film is made with a raw edge, enhanced by its cheapness and the sleaziness of its real locations.
The emotional high point of the film is the following scene, when the (dangerously) emotionally reserved Mineo dances with Prowse for the first time and it's sexy and dangerous all at the same time. They are both dancing in character and it's a hundred times more effective than an hour of dialogue could ever be. This is a special scene, enhanced by an amazing song by Bob Gaudio and Al Kasha, which somehow was never released as a single.