9. Vince Vaughn - The Lost World: Jurassic Park
There are few disappearing acts of major movie characters more distracting or baffling than that of The Lost World: Jurassic Park's documentarian-activist Nick Van Owen (Vince Vaughn).
Despite being one of the film's major characters, he randomly evaporates into thin air when the movie still has a whole half-hour left.
After boarding an InGen chopper with Ian Malcolm (Jeff Goldblum), Malcolm's daughter Kelly (Vanessa Lee Chester), and Sarah Harding (Julianne Moore), we never see him again, despite Ian, Kelly, and Sarah all having notable parts in the imminent San Diego T-rex rampage.
Stranger still, despite being played by a firmly on-the-rise actor in Vince Vaughn, Nick isn't ever even mentioned again, leaving fans to speculate on what exactly became of him.
After all, it's tough to imagine Nick just sitting around doing nothing during the events of Jurassic World Dominion in particular.