All it takes is one film to completely change how you feel about an actor.
In the cases or Nic Cage, Keanu Reeves or Adam Sandler, who show flashes of brilliance sporadically, the way audiences feel about those actors tends to be comically impermanent. And that has a lot to do with their inevitable return to dross.
Likewise, when a great actor slums it, it tarnishes their public image terribly, and adds a distasteful caveat to their former achievements. Nobody remembers Halle Berry as an Oscar winner, they remember her as the Oscar winner who then made Catwoman. That kind of thing tends to stick.
That's why actors tend not to deviate too broadly from their brand, no matter how much critics suggest it makes them truly great. Mainstream audiences just don't feel that way: they want Jim Carrey to be rubber-faced mugging Jim Carrey, they don't want him to suddenly be Johnny Depp.
That can seem terribly reductive, but it's also why performances that break the mould, or are as unexpectedly successful as Ledger's Joker or Keaton's Batman attract so much attention. It's also why comic actors go serious, and why comfortably pigeon-holed stars seek to challenge themselves and expectations.
So despite all of the pitfalls, some actors do try and reinvent themselves, and there are a number of upcoming films that might well shock fans - either positively or otherwise...
10. The End Of The Tour - Jason Segel
Jason Segel is a odd prospect, more often than not cast in variations of his How I Met Your Mother character: the model for nice guy relationship types who might get kicked about a bit, but who always end up doing ok. He's a likeable actor, but he's never pulled up too many trees actually performing.
That could soon change with The End Of The Tour: the most Sundance of Sundance films following Segel as tragic, accalimed author David Foster Wallace through the eyes of Jesse Eisenberg's David Lipsky.
The role, which will require Segel to capture not only Wallace's easy appeal and mythos but also the reality of his inner turmoil and depression is far more complex than anything he's done to date. And that could mean the Segel who emerges from it is entirely different to the Muppet loving comedy nice guy.
Will It Last?
Unfortunately, it doesn't look like The End Of The Tour is going to achieve anything like mainstream success, even if it entirely deserves to, so it's more likely he'll be back to more Sex Tape-like fare sooner rather than later.