A tentacle monster appears in the 1987 TV series episode "Splinter No More". However, Shredder accidentally opens a portal to the wrong place, causing the monster to appear in the Subterranean temple.
The Ninja Turtles, Splinter and April O'Neil team up with Shredder, Bebop and Rocksteady to fight the monster. The Turtles are able to trick the monster into collapsing the pillars, causing the ceiling to cave in, killing the monster.