Sheldon is a turtle that Stewie Griffin brought home as a pet, but was a homicidal maniac that tried to kill him and was a one-shot antagonist in Family Guy. He appeared in "Lois Comes Out of Her Shell" as the main antagonist; Stewie finds him in a pond in the park and decides to bring him home as a pet. What Stewie did not realize that Sheldon was a sociopath that wanted to kill him. It is unknown why he wanted to, but one reason is that he did not want to be taken from his home. He would pull sick sadistic jokes on both Stewie and Brian, making one mad at the other until Stewie realized that it was Sheldon the whole time.