The Space Squid has been referenced a few times.

• Jungle Law -- Skipper believed that the blackout in the zoo was phase one in the Space Squid invasion while Kowalski pulled out a comic book showing the Space Squid to Private who was disturbed by it.
• The Hidden -- Kowalski explained what could have attacked Mort as an unknown hostile with tentacles and feet. Skipper then became mad as if he had dealt with a similar hostile in the past. (although he could have been angry that Kowalski was relying on his intellect again)
• Lemur See, Lemur Do -- The Space Squid's tentacles were shown at the end attacking Lemmy (LEM-R).
• Alienated -- 1st full appearance. Here it hitched a ride back to Earth inside Lemmy. It collected several electronic devices to use to signal an invasion but it was stopped by Lemmy. That was the first episode where he was the main antagonist.
• I Know Why the Caged Bird Goes Insane -- The 2nd full appearance of The Space Squid. Where the Space Squid goes to the INVEXPO to steal some inventions but instead steals Kowalski's Extend-O-Grab in an attempt to master hand technology. He was forced to flee when Marlene pokes him mercilessly.
• The Trouble With Jiggles -- 3rd appearance of The Space Squid, shortly after revealing its plan to destroy Earth via a satellite laser, the Space Squids are then attacked by the Jiggli.
• Operation: Swap-panzee-- 4th appearance of The Space Squid. It made a brief cameo at the end when the penguins landed on Mars and The Space Squid pops up and scares them.