Thomas "Tubby" Tompkins is a mischievous boy with reddish-blond hair and a heavy build, typically clad in a white sailor hat, black collared shirt, and light brown or orange pants. He displays inflated self-regard yet lacks self-awareness, constantly seeking status and assuming leadership within "The Fellers," his neighborhood boys' club that enforces a strict "No Girls Allowed" policy. His flawed "kid logic" guides his interpretations and problem-solving, often disconnected from reality. He believes in male superiority and prioritizes food above all, viewing his weight as entitlement to more sustenance. His leadership faces frequent challenges due to his poor memory for obligations like paying club fees, resulting in repeated removals from office by the other boys. He acts as both friend and rival to Lulu Moppet, assisting her when needed while also tormenting her and serving as her antagonist. His romantic interests include Lulu and Gloria Goode Darling, though Gloria often prefers Wilbur Van Snobbe. Rivals include the tougher West Side Gang and Marty the Midget. Adopting the alter ego "The Spider," inspired by Sherlock Holmes, Tubby investigates imagined crimes, frequently suspecting Lulu's father. These detective pursuits often expose his own culpability, such as when he is revealed as the vandal of the city, provoking Lulu's anger and pursuit. His parents are called "Maw" and "Paw." Tubby engages in varied storylines: romantic triangles involving Gloria, Lulu, or Wilbur; battles of the sexes against Lulu and her friends; detective mysteries as The Spider; and fantastical adventures like encounters with the "Little Men from Mars," diminutive telepathic aliens seeking his help. His schemes, driven by flawed assumptions and unshakable confidence, often backfire. Specific episodes include cross-dressing to avoid recognition and babysitting scenarios managed by Lulu. In the anime adaptation, Wilbur Van Snobbe transitions from a snobbish antagonist to a supportive friend and occasional "Smart Guy." Gloria becomes one of Lulu's friends, softening the rivalry. Tubby's smaller lookalike cousin, Chubby, occasionally visits, much to Tubby's resentment.