The protagonist in the Jack Ryan films is actually named JOHN Ryan. I'm not too familiar with the book version of the character, as I've only read a couple of the books. The movies don't mention where the name "Jack" comes from, but uses "Jack" as of his first appearance in "The Hunt for Red October", and even in "The Sum of All Fears", which is chronologically set much earlier. I'm hoping a fan of the series can shed some light on the origin of that nickname.
Do any of the films containing Jack Ryan mention where he picked up the nickname "Jack"?