Squadward

Origin
Squidward Tentacles faked his death to enslave Spongebob and Patrick. Believing he was truly dead, they put him in a bubble to float him up to Heaven, but ultimately killed him. Squadward was stuck in Purgatory and saw everything he hated (this can be seen briefly at the end of "Spengbab Makes an Amalgamate". Squidward eventually returned to Earth as Squadward because he had never achieved his dream of becoming famous.

Story
Squadward Tentacles is the demonic ghost of Squidward Tentacles. He first appeared in Squidward: the unfriendly ghost. He resembles Squidward but paler and adorned in white towels and a bathrobe. He ruthlessly enslaved Spongebob and Patrick, turning them into the obsequious minions Squadbob and Squadrick. As cruel and sadistic as he is, Squadward looks sadly at Spongebob and Patrick as they first grovel at his feet following Squidward's death. This suggests that deep down he might feel some remorse for his inferiors. Squadward started a war that ended in his demise. Tem killed him with PK Love.