Pugsley Addams is a member of the fictional Addams family, created by American cartoonist . Pugsley is depicted as a devious young genius in Charles Addams's original cartoons. He is often shown releasing sailboats in the park with other children, except his boats were more macabre in nature.

Pugsley is the oldest child of Morticia and . He is a pre-teen boy (His age is given as eight years old in the pilot episode but is changed to ten years old in the second episode) who is almost always seen wearing a striped T-shirt and shorts. Originally unnamed (as were all of the family members), the character who was apparently the prototype for Pugsley first appeared in the Charles Addams cartoons in during the 1930s. In this first incarnation, he was portrayed as a deviant child with a vicious nature, shown committing deplorable acts with his sister. In all incarnations, he is overweight. In the television series, Pugsley usually eats over five pieces of cake at birthday parties.

When the characters were given names for the television series, he was originally going to be called "Pubert" (a derivation of the word puberty, possibly a reflection of his age) but it was rejected as it sounded too sexual, and the name Pugsley was chosen instead. The Lurch Files' Addams Family Tree lists Pugsley's middle name as Pubert, probably as an homage to Charles Addams' original suggestion.

In the American television series, Pugsley is played by child actor Ken Weatherwax. This incarnation of the character is more jovial and inventive; he displays outlandish engineering skills, including the invention of a disintegrator gun, an anti-gravity gun, and other devices. He and Gomez created a computer named Whizzo and a robot named Smiley (played by Robby the Robot). Pugsley and his younger sister Wednesday often play together, rarely exhibiting signs of sibling rivalry; they share an interest in spiders, dynamite, guillotines, and other dangerous "toys."

In an early episode, "Morticia and the Psychiatrist", the rest of the family is concerned that Pugsley is engaging in behavior they consider "odd": wearing a Boy Scout uniform, playing with a puppy, etc. When sent to a psychiatrist, Pugsley tells of boyhood incidents involving hangings, machine guns, and grenades, with no clue that others might find these accounts unusual.

In most incarnations of the character, Pugsley had an unusual hobby of stealing road signs, which he used to adorn the walls and door of his bedroom. This may have evolved from an original Addams cartoon in which, rather than road signs, he would steal and decorate his room with cautionary signs, such as high voltage and shallow water signs, thus leading others into danger. He also has a pet octopus named Aristotle.