"I’m the anti-fairy Cosmo. I’m not an idiot in any manner whatsoever!"
— Anti-Cosmo introducing himself to Timmy upon the Anti-Fairies being freed from their prison.
Anti-Cosmo Anti-Julius Anti-Cosma is the Anti-Fairy counterpart of Cosmo. He is the husband of Anti-Wanda, the father of Foop and also the acting leader of the Anti-Fairies. All three appear as major recurring antagonist in the series, and act as their counterparts of Cosmo, Wanda, and Poof respectively.
Since all Anti-Fairies are complete and utter opposites to their fairies counterparts, Anti-Cosmo is the total alternative to everything that makes up the original Cosmo.
While the normal Cosmo is amazingly dumb yet kind and caring, Anti-Cosmo is the opposite as he is an evil criminal mastermind and is very ruthless in his ambition to become more powerful so that he can cause even more bad luck among humans, an ambition shared by all his Anti-Fairies cohorts, of whom he is apparently the ringleader of.
Anti-Cosmo has a blue and black color scheme consisting of a blue bowler hat in place of a crown, fangs, and bat wings like those of all Anti-Fairies. He wears a monocle over his right eye which he cannot see without, and wears a kind of coat or suit and, unlike Cosmo, Anti-Cosmo speaks intelligently with a stereotypical British accent.
He is married to Anti-Wanda. Anti-Cosmo's castle is most likely not open to anyone except those Anti-Cosmo permits such as when the Pixies temporarily became his allies in "Fairly Odd Baby". Since Cosmo used to be the last Fairy baby ever born, Anti-Cosmo may have been the last Anti-Fairy baby ever born until Anti-Wanda gave birth to Foop.
Being Cosmo's complete opposite, Anti-Cosmo is far more intelligent, evil, and devious than most other villains in the show, let alone his counterpart Cosmo.
However, it is usually because of his dim witted wife, Anti-Wanda, that he fails at his plans, or otherwise Timmy gets the best of him. He is not been shown to get angry much (except with Cosmo who he regards as mind-numbingly stupid) and actually seems to usually take a curious delight when things don't go his way. He can be seen as a sore loser in Balance of Flour. And in Fairly Oddlympics he can be seen as a cheater.
"You see, we've been trapped behind that blasted barrier for centuries. But we knew on some Friday the 13th some child would be stupid enough to have his fairies bring him here and wish all of us free."
On Friday the 13th, the Anti-Fairies got loose and started wreaking havoc on Timmy Turner's trip to Adrenalland by causing bad luck all over the place. The Anti-Fairies were originally invisible, and could only be seen with a device that, when Timmy put on, he saw and met Anti-Cosmo. Being Cosmo's opposite, Anti-Cosmo was extremely intelligent and was respected as their leader who sarcastically congratulated Timmy for freeing them.
In his next appearance, Cosmo's Fagiggly Gland goes bad and he needs a replacement, and the only match is Anti-Cosmo, who escapes from captivity shortly after the transplant. Anti-Cosmo told Cosmo to not look for him, but Cosmo does not obey and finds Anti-Cosmo behind him. Anti-Cosmo then realizes part of Cosmo is in him before leaving while Cosmo displays some traits of Anti-Cosmo.
Later, Anti-Cosmo tries to frees his captive comerades, but fails due to Jorgen. Later with the help of Calamitous, Anti-Cosmo is able to free the other Anti-Fairies. One half of the group was sent to create so much bad luck while the other half was sent to stop the Earth from rotating to keep it at Friday the 13th. Because there are too many Anti-Fairies to undo the damage done through a wish, Timmy and his friends go to the Crocker Cave and find a butterfly net which should be sufficient on catching the Anti-Fairies. Jimmy combines the net with his hyper cube to create a trap for the Anti-Fairies. Jimmy's friends, Cosmo, Wanda, all create as much bad luck as they can. This lures all of the Anti-Fairies to the exact location, including the ones that were keeping the Earth from rotating. Jimmy then activates his hyper cube which captures all of the Anti-Fairies and traps them inside the hyper cube. It is unknown what happened to the hyper cube, but Jorgen most likely took it with him, so he could trap the Anti-Fairies back in their imprisonment again.
After he and the bulk of his race escaped from Fairy World's jail, most of the Anti-Fairies took up residence in Anti-Fairy World to plot their next move against Fairy World and Earth. After the first fairy baby in eons was born to Cosmo and Wanda, Anti-Cosmo plotted with the Pixies in an attempt to steal the young baby Poof before his magic could be controlled by the Fairies. They did not succeed and Anti-Cosmo and HP ended up being raisins for Jorgen's cereal temporarily due to Poof breaking wind on them.
Later Anti-Cosmo demands equality and is not happy that fairies are appreciated for things they create when Anti-Fairies have created things too. Anti-Cosmo then begins to question why there is no Anti-Fairy for Poof since there is supposed to be an Anti-Fairy for every fairy. He then notices the symptoms that Anti-Wanda had for anti-fairy pregnancy. Anti-Wanda then gave birth to Poof's Anti-Fairy equivalent, Foop, who is even more evil and untrustworthy than Anti-Cosmo. Foop betrays his race and turns Anti-Fairy World into a cute and cuddly place, much to its residents's horror. Despite this, after Foop was captured, the damage he did was reversed when Poof made him cry. He was then taken away to Abracatraz where he would be held for rehabilitation. Anti-Cosmo and Anti-Wanda then paid him a visit, hoping to slip him some tools to escape. Although Foop eventually did manage to escape, it was by his own devices and not with the help of his parents.
When Anti-Cosmo was first introduced, Timmy could only see him with special "Anti-Fairy Goggles" as all Anti-Fairies were invisible to humans. Anti-Cosmo mocked Timmy, saying that the foolish boy freed him and his ilk after centuries of captivity. In later episodes, Anti-Cosmo and the other Anti-Fairies are visible by Timmy without any need for special gear, and this concept of invisibility seems to have been dropped entirely. The Anti-Fairies may now be seen on Earth due to Jorgen taking away their ability to be invisible on Earth in Jimmy Timmy Power Hour 2: When Nerds Collide. However this does not explain how they can be clearly seen in "The Gland Plan" since that occurred before the former episode, however it is possible that the anti-flight and magic uniforms they were wearing prevented that since the Anti-Fairies’ invisibility may have come from their magic. In the episode "Balance of Flour" it is said that the Anti-Fairies and Fairies fought in ancient times to decide who gets to have godchildren, but they decided to settle this dispute by holding an annual baking contest. The Fairies always won every year from then on. This contradicts what Jorgen and Anti-Cosmo had said about the Anti-Fairies being kept locked up for centuries unless this was after the ancient times and the Anti-Fairies did something that was so unspeakable that caused them to be locked up for so many centuries.
Relationship with Anti-Wanda
"Oh, Anti-Wanda, I do love you so much, but you are such a twit!"
— Anti-Cosmo to Anti-Wanda in the Gland Plan.
Anti-Cosmo thinks of his wife much like Wanda does of Cosmo, a dimwitted but lovable spouse. Anti-Wanda is the opposite of Wanda, and she is mostly like Cosmo in personality and actions. They both share the same problems that Cosmo and Wanda do, but nevertheless they love and care for each other.
Relationship with Foop
From the very first day Foop was born, Anti-Cosmo's relationship with his son was on the very edge. After all he tried to act like a responsible father but Foop went overboard by zapping him. Deep down though Anti-Cosmo loves his child, and tries to help Foop escape by sneaking a nail-filer into his playpen cell at Abracatraz prison. Foop later escapes by his own means, and has not been seen with his family since.
Unlike the normal Cosmo who is dimwitted and always being told what to do by other fairies, Anti-Cosmo is a diabolical criminal mastermind and he is also the leader of the Anti-Fairies.
Anti-Cosmo has a British accent, while Cosmo does a terrible British impersonation.
Anti-Cosmo didn't give birth to Foop, who was instead born from Anti-Wanda.
Cosmo loves red meat (ex. Bacon and Weiners), so, Anti-Cosmo probably hates red meat.