Q: “Who is Ash's Father?”
A: No one truly knows, really.
He was mentioned, along with Ash's grandfather (Japan only) in the second episode of the original series. That was the first and last time he's mentioned in the show. There's absolutely no solid evidence to back up all the crazy crack theories and until the writers decide to reveal the identity of this mystery man (or mystery men, but no one really cares about Ash's grandfather, right?
), we'll never know who he REALLY is. We know that he's a Pokemon Trainer, that's for certain. The way his mother talks about his alleged relatives in the Japanese version implies that being a Pokemon Trainer runs in the family. Other than that, we know zilch.
Novelizations of the anime by Takeshi Shudou (one of the writers for the original series) says that Ash's father is merely a wandering trainer of sorts, or something to that extent (although, whether or not these should be considered "canon" is debated among fans). In a recent interview with Masamitsu Hidaka, a storyboard artist for the anime, the above is confirmed and is very much true - Ash's father and grandfather are trainers. Not to mention, Ash's father is very much human.
Courtesy of Satoshi