Spin-Offs of Popular Game Franchises - Game Sack

Sometimes companies just can churn out the proper sequels fast enough so they attempt these "side-stories" that take place away from the series proper but are still "canon". Sometimes these use side-characters instead of the main ones but sometimes they're just new adventures in a different style. For example the Tomb Raider spin-offs still star Lara Croft but there's no mistaking them for a main-entry Tomb Raider game. Others will completely change the play mechanics around, like Metal Gear Rising does compared to its main series. Others try to be main entries into the series, like Shadow the Hedgehog, yet they do not star the main character. What are some of your favorite spin-off games?