The complexion, like [that of] Morticia, is dead white, the eyes are pig-like and deeply imbedded, circled unhealthily in black—no teeth and absolutely hairless.

Uncle Fester is a completely hairless, hunched, and barrel-shaped man with dark, sunken eyes and often a deranged smile.

Nevertheless, the character is recognizable in a number of cartoons, both by his appearance (bald, stooping, sunken eyes) and eerie behavior (turning the shower to a special "scalding" setting, feeding his garden plants blood plasma, and releasing an eagle to attack the neighbor's homing pigeons).

He relieves the migraines by placing his head in a large screw press and tightening it to levels that normal people would not be able to withstand.

He shows great respect for Gomez and Morticia, and always exhibits love and concern for his niece and nephews, despite their frequent naughtiness.

In the series Wednesday, Fester still possesses his electric powers and a great affection for his niece, but is portrayed as more roguish, appearing at Nevermore Academy looking for a place to hide out from the law, saying that he used to keep Gomez on his toes by dropping "from the ceiling, with a dagger clutched between my teeth".

In various episodes, he was a partner in typical sitcom schemes with Gomez, Morticia, or Grandmama Addams, indicating no real preference for any family member over others.

Sometime prior to Morticia's marriage to Gomez, Fester worked as a newspaper columnist, writing advice for the lovelorn, but left that job because people kept suing him.

As an adult, Fester took correspondence courses in various subjects, and his educational endeavors occasionally formed an episode's main plot.

It may be from one such course that he obtained his fraternity paddle, which he once threatened to use on Wednesday in imitation of his father's punishment style; however, like many an uncle, Fester proved to have more bark than bite in dealing with the children.

When he suspects someone of maligning, cheating, or otherwise mistreating anyone in the family, Fester is ever ready with his blunderbuss "Genevieve", eager to "shoot 'em in the back!"

Every morning, Armisen's head was buzzed smooth, makeup and powder were applied to make him look paler, and dark circles were added around his eyes.

Fester seems quite oblivious of the fact that Norman hates him and, possibly due to the Addams family nature, thinks that all the angry and aggressive outbreaks are a sign of affection.

A loan shark named Abigail Craven (portrayed by Elizabeth Wilson) conspires to steal the Addams fortune using her son Gordon, who displays an eerie resemblance to the missing Fester.

Although he is baffled and horrified by the Addamses at first, Gordon begins to take a liking to the family and their strange ways, feeling more at home with them and increasingly conflicted over Abigail's manipulations.

It is revealed that he actually is Fester; his disappearance left him suffering from amnesia, and Abigail duped him into believing he was her son until the lightning restored his memories.

The strike also gives Fester the ability to conduct electricity and make a light bulb glow by putting it in his mouth.

He becomes attracted to Debbie Jellinsky (portrayed by Joan Cusack), whom Gomez and Morticia have hired as a nanny to care for their children.

Debbie marries Fester with the intent of killing him and inheriting his share of the Addams fortune, but he survives each attempt on his life.

Some time later, Fester becomes attracted to Dementia (portrayed by Carol Hankins), a nanny whom Cousin Itt and his wife have hired to look after their baby.

He is also the main character in "Electrifying" arcade machine, where simulated "electrical shocks" are passed through the player as they hold on to two handles.