Mr. Tentacles is Squidward's father and Mrs. Tentacles' husband. He has not appeared on screen, but was mentioned in Krab Borg when Squidward claimed that his father loved him very much. The use of past tense has led to fan speculation that Mr. Tentacles is deceased. However he made a live appearance in the book Hooray for Dads!, indicating he's alive. Mr. Tentacles was shown to have a similar personality to his son. He wears glasses.
Besides Mr. Krabs, he is the only dad in the book Hooray for Dads! who didn't have a mustache.