A Gym Leader in Pokémon games and anime series. Tall guy with dark, "spiky" hair. Keeps eyes very narrowly open (never opens them enough that we could see the color of the eyes..). Single and can't resist lovely women. He's often described as the Captain Obvious of the series, always stating the deepest foundation of the issues... =)
He's famous for developing various Pokémon training methods and making very good Pokémon food. Also the cook and chief bottle washer of Ash's company.
Has Onix, Geodude and Vulpix (whom he got from Suzie, a fellow training expert - he gave Vulpix back later on).
He leads the Pewter City gym. In the beginning of the story, Brock was responsible not only to lead the gym, but also to feed the family, several brothers and sisters of his. After Ash beat him, his father took care of the family and Brock joined Ash's company.
(The latest was IIRC. Brock joined the crew early in first season of the show, it's been a while since I last saw the episode.)