Neville Longbottom.
"Well if that's how you really feel, Neville self-destwuct."
---Neville's last words before committing suicide
Neville Longbottom only appears in "Wizard Swears" and "Neville's Birthday." The puppet was a butternut squash on a stick, unlike the other characters, which are made of felt. Neville has a childish voice and speaks a little like a duck. The way he says things makes "Hagrids's buttcrack" sound like "Hagrid's buttquack." He said this because Harry, Ron, and Hermione dared Neville to say a wizard swear.
Neville on his birthday
Neville returned in "Neville's Birthday," where it was his birthday (age unknown) and everyone abused him. He also committed suicide in the episode by self-destructing after Harry, Ron, and Hermione told him that no one ever liked him. Neville also had alternate appearances for when he showed obvious emotions in this episode.
Ghost Neville
After his death, everyone ate his remains (even Snape) playing on the fact that he is a butternut squash. After a few seconds, Neville's ghost jumps out in front of the screen and says, "It's what's on the inside that counts." and winks.