A great, truly surprising cameo can help take a film to new heights, like with Bill Murray's incredible scene in Zombieland, or Glenn Close playing the pirate Gutless in Steven Spielberg's Hook.
On both occasions, though, the actors were credited, despite the attempts to hide Close at least. Likewise, King of Cameos Matt Damon gives a brilliant, hilarious turn as Loki in Thor: Ragnarok, but rumours as to his appearance had already started swirling well before the movie's release.
What's really great is when an actor - and all others involved with the film - manage to keep things under wraps not just before the film, but ideally during and afterwards as well. They don't do any publicity for it, the characters they play are hidden under mounds of make-up, prosthetics, or CGI, and rather than taking a mention on the billing they either go uncredited or decide to use a pseudonym.
Of course, they get revealed eventually, either thanks to some eagle-eyed viewers or because it's just so much fun that those involved have to brag about it, but before that happened all of these did a remarkable job of keeping their roles a secret.
NCTJ-qualified journalist. Most definitely not a racing driver. Drink too much tea; eat too much peanut butter; watch too much TV. Sadly only the latter paying off so far.
A mix of wise-old man in a young man's body with a child-like wonder about him and a great otherworldly sensibility.