* CareerResurrection: Ultimately what hosting ''LateNight'' (and later ''TheTonightShow'') did for him. Up to that point, he'd had some success on SNL and at least one film that did moderately well critically (''Fever Pitch''), but that was followed shortly by the dud that was ''Taxi'' (with Queen Latifah), and there were quite a few who thought he'd fade into obscurity. The criticism for his Corpsing on SNL didn't help his reputation, either. However, after developing some recurring bits over his first few months on the show (and hosting the 2010 Emmys to great success), his reputation was saved.
* CrowningMusicOfAwesome: Any time he does his Neil Young impersonation. He even got the real David Crosby and Graham Nash to perform with him! And then there's his rendition of "Whip My Hair" with BruceSpringsteen...
** History of Rap parts 1 & 2 with assistance from The Roots and JustinTimberlake
* HilariousInHindsight: The ''WesternAnimation/FamilyGuy'' episode "Don't Make Me Over" depicted Jimmy Fallon as the host of a fictitious episode of ''SNL'' with the Griffin family (featuring a made-over Meg) as the musical guest (and Peter beating up Fallon for cracking up on-camera since only Caroll Burnett has earned the right to do that, not realizing that Fallon had sex with Meg as part of the show's cold opening). Why is this HilariousInHindsight? [[spoiler:Because Jimmy Fallon actually came back to host ''SNL'' for a Christmas episode in the show's 37th season. The musical guest, however, wasn't The Griffin family or even SethMacFarlane -- though he would host the first episode of season 38. It was Michael Buble]].
** The 1998 (season 24) Christmas episode hosted by Alec Baldwin [[note]]It was the one with the Schweddy Balls sketch[[/note]] had a ''ItsAWonderfulLife''-meets-''Literature/AChristmasCarol''-style story that shows what the future will be like if Alec Baldwin phones in his performance on this episode. The episode predicted that in 2011, Fallon would come back to host ''SNL''. It came true (only the date they gave in the 1998 episode was inaccurate, as December 12th, 2011 did not fall on a Saturday).
* HoYay: With JustinTimberlake. So much that during Justinís impromptu speech at his wedding reception in front of 150 guests, Jimmy interrupted him with a joke from his seat, sparking an improv between the two of them that went on for a good five or 10 minutes and had all the guests roaring with laughter. Justin admits that if it was anyone else, he would have kicked their ass.
* JustHereForGodzilla: With The Roots as his backup band people who don't like his comedy claim they only watch his show to see them.
* TheScrappy: On ''SNL'', particulary during the show's 28th and 29th seasons, when he gained notoriety for cracking up during his sketches.