Thaddeus is a light green cucumber fish who is a citizen of Bikini Bottom. He wears an orange shirt. He is often seen at the Krusty Krab.
- The name is homage to Thaddäus Tentakel, the German name for Squidward. The German dub subsequently changed his name to Fischward to avoid confusion.
- According to the episode "Krab Borg," Thaddeus is not a robot.
- "Where's our food?!"
- "No, I'm not."
- "Or knitting fluffy sweaters!"
- "Uhh, I think I'll have a Krabby Patty!"
- "I got the clarinet!"
- "Hey, I didn't order a table patty!"