Casting decisions you can't believe worked but they did.

[Svengoolie 3]

Robin Williams as teddy Roosevelt in 'night at the museum'.

Raul Julia as Victor Frankenstein in Corman's "Frankenstein unbound".

Tom Cruise as Lestat in " interview with the vampire".

[indianasmith]

I had always envisioned Sean Connery as Gandalf, going all the way back to junior high.
I would speak the Gandalf lines from THE HOBBIT in my best Sean Connery voice when I read the book to my kids when they were little.
Then they cast Ian McKellen in the role - I had seen him in RICHARD III and  APT PUPIL, but I really didn't think he could make the leap to Gandalf.
But he did - and he ROCKED it!

[claws]

Mike Myers as Steve Rubell in 54 (1998)
Michael Keaton as Batman in Batman (1989)

[Alex]

Robert Downey Jr in Iron Man.

[FatFreddysCat]

Ben Affleck as Batman. All thru "BvS" (which kinda sucked), all I could think of was how much I would've rather been watching Affleck in a solo Batman flick.

[Trevor]

The South African raised and educated actor Laurence Harvey as Colonel Travis in The Alamo (1960)

[The Burgomaster]

Daniel Craig as James Bond. When it was first announced, I looked at his photograph and said, "How can that POSSIBLY be 007?" But I think it worked out fine.

[RCMerchant]

Daniel Craig as James Bond. When it was first announced, I looked at his photograph and said, "How can that POSSIBLY be 007?" But I think it worked out fine.

I thought the same thing. "He's BLONDE!" Your right. He's the best since Connery.

Charlize Theron in MONSTER (2003). I mean Charlize is beautiful! But as Aileen Wuornos???
Of course she pulled it off amazingly.

[HappyGilmore]

Joaquin Phoenix as Johnny Cash in Walk the Line.
Hugh Jackman as Logan/Wolverine.

[voltron]

Tom Cruise in Eyes Wide Shut.