Actors turn down roles all the time. It's part and parcel of the whole gig. You never know which roles are going to go on to be super iconic, after all - it's a guessing game with impossible rules and twists and turns nobody really understands. A role that looks average on paper could end up being the opposite on the big screen, whilst a seemingly awesome one could wind up being misjudged or contained within a flop.
As William Goldman once famously stated when talking about the unpredictable nature of Hollywood and all its trappings: "Nobody knows anything." No sh*t, Will.
What that doesn't mean, however, is that actors don't ultimately regret turning down parts that went on to be incredibly fruitful for other actors.
In the case of the following eight movie roles, the actors in question turned them down because of scheduling conflicts, out of fear, or because they thought the movies were going to plainly suck, never realising that they'd just waved goodbye to some of the best roles of all-time. Naturally, they regret doing so... because what idiot turns down these iconic parts?
Due to her iconic role as Elle Woods in the loveable "law-based" comedy flick Legally Blonde, Reese Witherspoon was launched to the top of the A-list; as a result, she went on to be one of the most in-demand actresses in Hollywood. Interestingly, though (as always seems to be the case with iconic roles), she wasn't the first choice for the part.
Christina Applegate - perhaps best known nowadays for her turns as Ron Burgundy's love interest Veronica Corningstone in the Anchorman movies - was actually offered the role of Elle Woods but turned it down because she was afraid of playing another "dumb blonde" so soon after playing one on TV's Married... With Children. In her own words:
The script came my way, and it was after I had just finished Married [...With Children]. I got scared of kind of repeating myself. What a stupid move."
Applegate has gone on record to state that she sincerely regrets turning down the role (of course she does!), but also thinks that Reece Witherspoon did a better job that she ever could have. Applegate might have proven herself to be a worthy Elle Woods, but it's hard to imagine anyone other than Witherspoon as the character. You win some, you lose some.