Liam Neeson was reportedly offered the role of James Bond in 1995s Goldeneye. He reportedly turned it down because he wasn't interested in starring in action movies! Of course, he would revert that decision only 4 years later when he starred in Star Wars, Episode I. He must have really regretted it because he also showed a particular set of skills in his 2008 movie Taken that would have made him a great 007.
It's interesting to think, though, what could have been if Liam Neeson had been James Bond, instead of Pierce Brosnan. Interestingly enough, on the list of rejected actors for the role of Bond is Robert Pattison "because his image of being dirty and possibly his age."