This list may include games I have not finished (but played enough of to get a good impression)
How am I defining a platformer for this list? Not strictly collect-a-thons, but a game that is designed around platforming to reach a certain goal.
Puzzle-Platformers like Portal will not be included. Games that simply include platforming as an element will not be included unless it is considered a main mechanic or selling point of its gameplay. An example of this would be Ratchet & Clank being included. It has a focus on action and shooting, but platforming is equally important to the design of its gameplay and levels. One more example would be lego star wars being excluded despite it having platformer elements. Lego games are more focused on the action adventure aspect and therefore wouldn't fit in with this list.
Yeah, this is a little complicated but I think that these games being on a list together will at least make sense. There are games I may have forgotten due to the size of this list so it is always subject to change.