Ash's father

Ash's father is the unnamed father of Ash Ketchum from the Pokémon Anime series and husband to Delia Ketchum.

Background
From very minor portions of dialogue, it can be assumed that his father started on a journey from Pallet Town much like Ash. Never formally introduced, the identity of his father has always been under heavy speculation. These speculated characters however, have attained no hard evidence that they are in fact related to Ash in any way. In addition to that, during an interview with a storyboard artist for the Anime series, the artist stated that Ash's father is a man who is on his own Pokémon journey as a Trainer's.

Trivia
In The Spell of the Unown's commentary, the producers announced that more about him will be revealed in season 5, which eventually turned out to be untrue.