Jack Dawson (Titanic)
According to plan A, Matthew McConaughey would have played the main role of the movie.

The director (James Cameron) originally wanted to give Matthew McConaughey the lead, but the actor refused to take part in the movie. The second choice in line was Leonardo DiCaprio, who took on the opportunity and pulled off the character of Jack Dawson as if it was personally created for him. Let us share a fun fact with you: if DiCaprio turned down the role, it would have been given to either Christian Bale or Macaulay Culkin.