Michael Sheen's role has been axed from the upcoming Pixar film
The Masters of Sex star admitted being "very sad" about his voicework in the Finding Nemo sequel being cut, but said the snub had been a good check for his ego.
Speaking at Into Film 2016, he told Magic Radio: "I got a phone call saying I'm not in that (Finding Dory) anymore, they cut me out.
"Unbelievable. I was very sad, I was such a fan of Finding Nemo, but that's the way it goes, especially with animated films, you never know what's going to make it to the final cut.
"It's always a good thing to remember - you can always end up on the cutting room floor."
The Golden Globe-winner did not reveal what character he was due to play in the film, which follows amnesiac blue tang Dory (Ellen DeGeneres) on her mission to find her long-lost mother and father.
But he will definitely be returning for the sequel to Tim Burton's Alice in Wonderland, to release in May.
Sheen reprises his role as The White Rabbit in James Bobin's Alice Through The Looking Glass, alongside a voice cast that includes Stephen Fry, Dame Barbara Windsor and the late Alan Rickman.
Finding Dory will be released in New Zealand on June 23; Alice Through The Looking Glass will release on May 26.