[2] Kapičić was born 1 December 1978 in Cologne, West Germany,[3] the son of Slobodanka "Beba" Žugić, a Montenegrin actress, and Dragan Kapičić, a retired Serbian basketball player.

His grandfather Jovo Kapičić bought him his first comic book when he was six years old, which sparked what he called an "ongoing love" in a 2015 interview about his role in Deadpool.

[4] Kapičić played the role of his own father in the 2015 film Bićemo prvaci sveta (We Will Be World Champions) about the Yugoslavian national basketball team which won the 1970 FIBA World Championship.

Working with first-time director Tim Miller in Los Angeles, Kapičić did 120 takes during his third call of auditions, stretching the session an additional eight hours beyond its intended four-hour duration, before flying back to Dubrovnik, Croatia to perform Romeo and Juliet.

Kapičić, a self-described "comic book geek" who considered Deadpool one of his favorite characters, was especially delighted when he learned he won the role, taking over from Daniel Cudmore, who had played the role in the X-Men films.