Krackenstein is the antagonist in the Randy Cunningham episode "Last Stall on the Left". He was a giant, six-armed monster Viceroy created to destroy the Ninja. He was the first monster Randy fought as the Ninja.
Its vocal sound effects were provided by Fred Tatasciore.
Following Randy appearing at School, while coincidentally McFist was there, he quickly ordered Viceroy to send in his monster.
Krackenstien broke down the doors and attacked. Unused to fighting, it managed to knock Randy about, but he managed to stop it by locking it in the basement.
So the Ninja would come back, Howard quite foolishly let it out. It continued its rampage destroying the grounds.
Randy took him on again, this time he fared much better, even knocking him down, but he managed to over power him with his secret in his chest. However at that moment Randy found his sword, sliced of his arms, and defeated it by slicing the monster to pieces.