Most Jarring Recasts

I'm sure you've all been victim to the recast monster. It takes no mercy for greed, on-screen sheninigans, or scheduling conflicts. It has no reason, no sense of remorse, or even common sense. It is willing to break your suspension of disbelief and continuity just for fun. Here are just a few random recastings that I though of which make little to no sense.

Victoria - Twilight series
Perhaps the most recent of these offenses is Bryce Dallas Howard taking over for Rachelle Lefevre in the third of the Twilight series. The official reason was cited as scheduling conflicts. Obviously having not seen the upcoming Eclipse, I cannot pass judgment on the new interpretation of the Victoria character, but the filmmakers should have exercised a bit more caution when dealing with riled-up 14-year-olds and Twi-moms. They seem to take this stuff seriously.

Kristen - Nightmare on Elm Street Part 3 & Part 4
From what I can gather, Patricia Arquette was unable to return to the role of Kristen for Nightmare 4 due to pregnancy. A valid reason but that doesn't make the shift any less jarring, especially considering they were able to bring back Joey and Kincaid with the same actors. It would be one thing if the whole bunch was recast like the Griswald kids, but having two of the three return is a bit awkward.

Jack Ryan - Hunt for Red October, Patriot Games & Sum of All Fears
Jack Ryan is a rather popular character in the paperback world having been featured in twelve novels by Tom Clancy. Yet we have only four movies over the course of twelve years played by three different actors. The constant changing of James Bond seems to actually help the series reinvent itself. While Jack Ryan could have (or possibly still) become as household as Jason Bourne, he is not an established cinematic character and thus, the series suffers from the constant delays and turnover.

George McFly - Back to the Future series
Originally portrayed by Crispin Glover, subsequent sequels in the series used a different actor for the character of Marty's father. There are conflicting stories about why the character was recast from the favorite "creative differences" to Glover requesting an unreasonable sum of money to reprise the role. As such, the character was killed off in the sequel and barely featured in the third, minimizing what was an integral part of the series. While the stories make Glover rather buffoon-ish for not returning, the producers dealt with it in an interesting way, hiding the replacement actor behind make-up or creative camera angles.

Jamie Lloyd - Halloween 4, Part 5, & Part 6
This is the recast which pissed me off the most as the lovely Danielle Harris was kicked to the curb for a cheaper replacement, only to have the character killed off in the first ten minutes of the film. Actually, I might have been more pissed to see such a beloved character played by the same actress meet such a fate. Perhaps the producers were attempting to do us a favor to distract us from the sheer awfullness of the film. But I'm still pissed about it.

I could go on all day but I will stop here. What are some other recasts, good or bad, that caught you off guard?