Tom Clancy's complex protagonist for the series of books he wrote starting with The Hunt for Red October, which leads to the last published book (for now), Rainbow Six. He is a Intelligence Officer who is a master of his craft, and ends up saving the world a few times. Good stuff, complex plots, complex characters, no spoilers here though.

The protagonist of a majority of Tom Clancy's novels. Graduated from Boston College, went on to become a marine, during which time he suffered a near-fatal and crippling accident in a helicopter crash. Was a consultant for CIA for a time, then became a professor in history at Anapolis. Went on to various positions of state, eventually ending up as president as a result of a cataclysmic destruction of the convened House of Representatives, the President, and the Cabinet.

Jack Ryan has been played by both Alec Baldwin and Harrison Ford in the movie incarnations of the Clancy books. Personally... if you know Jack Ryan you come to the conclusion that Alec Baldwin makes a much better Jack Ryan than Harrison Ford. Jack Ryan is a desk jockey who sometimes ends up in the wrong place at the right time. Harrison Ford is too macho to be a desk jockey. Alec Baldwin just fits the Jack Ryan image better I think.