Best & Worst accents performed in a movie

[AndyD]

I thought this could be a good topic for discussion but also a cringe worthy one at the same time.

I would like to know the members opinions on what are the best & worst accents performed by actors in film. Whether the movie is popular, well known or a straight-to-dvd crapfest, it doesn't matter. Just give the actor/actress name, the movie, what accent they did or tried to do and whether it was good or not (in your opinion of course).

You can get into specific regional accents if you want.
I imagine bad accents are going to outnumber the good but we'll see.

Also, please comment only if you know what said accent really should sound like and not what you imagine it in your head.

OK, I'll get things started...

Good

Leonardo DiCaprio - Blood Diamond - South African accent: I thought Leo pulled off a terrific South African accent here.

Brad Pitt - Snatch - Irish (traveller/gipsy) accent - For what it was, Pitt actually did a very good job with this accent.

Christian Bale - Dark Night trilogy - American: Bale can pull off a solid American accent with little effort it would seem

Bad

Julia Roberts - Michael Collins - Irish accent: No Julia...just no.

Richard Gere - The Jackal - Irish accent - Awful Irish accent from Gere here

Michael Fassbender - X-Men: First Class - English accent: He didn't hide his Irish accent well enough in the latter half of the movie IMO. This ones open for debate here since his character is not actually English but as he becomes Ian McKellen's Magneto, I'm commenting on the English accent

Mel Gibson - Braveheart - Scottish: Not a great accent here. Not truly awful but still falls into my bad category