Abner is Arnold's pet pig in the Hey Arnold! TV Series.
Abner was given as a wedding gift to Arnold's parents, Miles and Stella, from the "Green-Eyed people," who they helped save ("The Journal"), even though Grandpa Phil wanted to barbecue him on the spot.
Stella first mistook Abner for a sow (a female pig) and wanted to name him "Abigail" until she learned that he was a boar (a male pig). Abner's best talent is digging out truffles. Abner is usually voiced by Craig Bartlett. Most likely, Abner was born in San Lorenzo, and is older than Arnold, as potbellied pigs can live up to 15-20 years.
He is shown to be like Arnold's best friend (next to Gerald, of course). Arnold has been shown to be completely devastated when Abner is in any danger; such as going missing (Abner Come Home), and even more so when he is captured and nearly barbequed (The Pig War).
He made his first appearance in "Eugene's Bike."
He has gotten fatter in Hey Arnold!: The Jungle Movie.