This location is the headquarters of Anti-Cosmo, and acts as his evil lair. It is here where the Anti-Fairies gather to discuss their plans for world domination. Anti-Wanda also gave birth to Foop here in the episode, "Anti-Poof". The sign over the castle's entrance says "Anti-Cosmo's Castle Welcome. Not!"
The castle is colored black and dark blue, with sharp spiked towers and a purplish colored Rainbow Bridge covered with spines. The castle is usually seen surrounded by dark or red ominous clouds.
Anti-Cosmo's castle first appeared in "Fairly Odd Baby", where Anti-Cosmo was seen plotting alongside his fellow Anti-Fairies. It was also seen as a fish bowl version in "The Fairly Oddlympics" The castle was also seen in "Anti-Poof" where Anti-Cosmo was despising the fact that Fairies are worshipped for their accomplishments while Anti-Fairies don't get any of that. Anti-Cosmo was also despising the fact that there was no Anti-Poof despite that there should be an Anti-Fairy for every Fairy. After seeing some of the strange traits that Anti-Wanda was going through, Anti-Cosmo realized that Anti-Wanda was going to have a baby. This led to Foop being born which Wanda was able to sense due to her motherly instincts.
- Fairly OddBaby
- The Fairly Oddlympics
- Balance of Flour
- The Terrible Twosome
- Scary GodCouple (mentioned)
- Man's Worst Friend
- A Fairly Odd Summer
- Return of the L.O.S.E.R.S.
- Blue Angel
- Certifiable Super Sitter (mentioned)
- The Castle was first introduced in Season 6 of the TV series.
- It's the opposite of Cosmo and Wanda's Castle.
- Foop was born in the castle.
- The castle is up in the sky where Cosmo and Wanda castle is underwater, and is much more spacious on the outside.
- Even though Anti-Cosmo no longer appears in the series, the castle still makes appearances due to also being the home of Foop.