Hagrid’s father was a human who had a child, Rubeus Hagrid, with a giantess named Fridwulfa. After Fridwulfa abandoned her family when Rubeus was very young, Mr. Hagrid raised his half-giant son as a single father. He died while Rubeus was a second-year at Hogwarts (GF23).
Other canon notes and references
One of Rubeus Hagrid's worst memories was of his father's death (PA11).
Nowhere in canon does it state that Hagrid's father was a wizard, although it seems likely since Muggles don't even know that giants exist.