Is he a minority

??????

both of his parents were white, but choosing Hispanic on a census form does grant minority status

No. He changed his name because Martin Sheen sounds better than Ramon Estevez. Simple as that.

It's also the same reason why his son stuck with Emilio Estevez because it sounded better than Emil Sheen, and he became a huge movie star despite his Spanish name thus proving it had nothing to do with being perceived as a minority but rather the sound of the name.

Martin's father was from Spain and his mother from Ireland. He anglicized his name mainly because he identified more with his Irish side, and still spends a lot of time in Ireland and even went to university there recently.

If you're one of those people that thinks Spaniards aren't white, then Martin's father was from Galicia, which is in the far north of Spain where the people look like the rest of Europe, as opposed to the south of Spain which was invaded and occupied by arabs for centuries thus they look a bit different.