Grandpa Gohan when he found Goku
Grandpa Gohan ia the Adoptive father of Goky, even though Goku calls him Grandpa Gohan. Grandpa Gohan is Goku's first teacher in the art of fighting. He is the one that found Goku has a baby. Grandpa Gohan was killed by Goku when in his Oozaru form.
Grandpa Gohan when he came back to life for a day
Grandpa Gohan in Dragonball Evolvtion