Lip This article is a stub. You can help Greenytoons Universe Wikia by expanding it.
Best. Season. Ever.
— Marketing slogan

Season 21 was a season of Greeny Phatom. JawLocker's Revenge is the first episode of Season 21, which aired on January 3, 2016 while The Pokemon Omega Ruby and Alpha Sapphire Release with Smash Bros Extra was the second episode of Season 21. The third episode is a "two short" episode has two segments, one of which is named Kelly's Big Score, which features Kelly, and the second is named Toilet Paper Man and is about Gittle Luy introducing his alter-ego, Toilet Paper Man. The three-part episode Greenytoons on the March! is a crossover between most Stainton Enterprises-owned animated series and properties. The fourth episode was The Beanson Gang and will be about... well..... the Beansons. The fifth episode will be "Birthday Idiots" and will be about Little Girl's 35th birthday party being invaded by terrorists, and hilarity ensues. The sixth episode was Greeny Phatom at Minecraft, and will be about Little Guy and his friends going on an adventure at the Minecraft universe. The seventh episode was Lee Doodle and is about Stink Guy being dared by Violet Lee to hoverboard naked to Little Guy and back. The Eight episode was The Mystery in GoAnimate City and is about when Little Guy fell into a hole into GoAnimate City. The ninth episode was The Rock 'n' Roll Horror Picture Show, and it is described as "A concert by The B-52's and the Little Girl Clones and their idiocy... nothing can go wrong, surely?" The tenth episode was The Shopkeeper, the show's first TV-14-DLSV episode, about the characters having to deal with the biggest racist on the show and his "whites-only" ShopRite. The eleventh episode was U Got Me Bugged, where DEVO come to town to play a large concert.

The season was originally going to be "the loopiest season ever" as all episodes and the intro were to be based on all episodes of Coconut Fred's Fruit Salad Island, however, after huge outcry, the basis was redone.

This will be the first season to have Sharpness Knight Animation Studios and recently-acquired Bardel Entertainment and GreenyWorld Studios Austin join the Greeny Phatom animation group. This will also be the first season (since Season 18) to have Michael Wildshill return as the executive producer. Also, many other old staff are returning to their jobs, to work on more episodes of Greeny Phatom. Jake Sanford, Kristian Michaels, Janna Dubinski and Barūn Kameyama also became full-time production team members.

New writes also join the team, including (but not limited to): Anne Beatts, Chevy Chase, Marilyn Suzanne Miller, Rosie Shuster, Alan Zweibel, Dan Aykroyd, James Downey, Brian Doyle-Murray, Don Novello, Brian McConnachie, Walter Williams, Tom Gammill and Max Pross, Phil Lord and Christopher Miller, Douglas McGrath, Christopher Parker, Tad Stones, David Wise, Warren Hutcherson, Ian Maxtone-Graham, Peter Harness, Mark Gatiss, Wayne Quick, Frances Bean Cobain, Courtney Love, Glenn Rockowitz, Aaron Fetcher, Richard Coz, Adam McKay, and Steven Moffatt. Most of them will be writing against type, since they're writing for a TV-Y7 show. However, Season 21 will be the first season to have some episodes rated TV-PG, TV-MA-DLSV, TV-14, and TV-14-DLSV, as Robert (the creator of the show) wanted the team to "break boundaries, and then some".

The purposed Little Guy Mystery Movies (The Lightsaber Thief (which became the episode "Kelly vs. the Evil Ninjas of Genericland", The Revenge for Salisbury (which became the episode "Violet Lee is a Pretty Woman", The Battle for Memy9909 and Joey Slikk (which became the episode "Born to be Stupid"), The Rambo Brothers' New Ops (which became a spoof of the post-Start to Read Signs episodes called "HABBADABBAZABBADABBA"), The Rampage for Gree Guy, Pingux2012 and Cookie Eater's Revenge, The Babysitter's Murder, The Stolen Chipwich (which became the episode "We Love Chipwiches"), The Scream, Spyro the Dragon (which became the episode The Dragon), The Infested Game (which became the episode "Creepypasta in a Nutshell"), The Cupcakes Killer (which became the episode "Another Ian Maxtone-Penned Episode!"), The Soul of Carrie (which became the crossover episode "Little Guy and Raggedy Ann & Andy vs. Annabelle"), The Prisoner of Arkatzand (which became the episode "Please Stop It with the Horror-Themed Episodes"), The Shadow of Dark, The Last Spirit, The Mirror of Death, The Wiggles' Revenge (which became the episode "BLEEP Returns"), The Ribbelation of Bryan Guy (which became the episode "Bryan's Favorite Way to Get Annoyed by Angry Fans"), The Brindis of Santed Sailor (which became the episode "Chipwich Land")) were turned into three-part episodes and rewritten entirely in Season 21 and Season 22

5 days are taken to make a single episode for Greeny Phatom Season 21, except for few episodes.

The series will start airing on Fox Kids, and The Greeny Channel. Starting from Season 21, the show will air on Tuesdays, Wednesdays, Thursdays and Sundays, instead of every 5th day of every month, because of how big the production team is.

The season ended on December 15, 2016, with a Christmas special aired on December 24.

The season had 204 episodes, when not including the Christmas special.

The Coconut Fred styled episodes originally for this season will be moved to a special DVD called "Greeny Phatom: Island Fun"