What are some fictional stories that contain someone having to complete tasks/challenges?

[takkid]

By tasks I mean those akin to the Labours of Hercules, where the hero (or anyone really) has to complete a certain number of difficult challenges for whatever reason. Media doesn't matter, just so long as the information is easily accessibly.

EDIT: Gah, I'm really sorry about the wording, I don't know what I was thinking.