Doore

Doore is a member of Cooler's Armored Squadron under the Planet Trade Organization. Long-haired, always seen with a helmet, and vaguely "Hulk"-like in appearance, he accompanies Cooler along with the rest of his team to Earth in the hunt for the Saiyan that defeated Frieza.
Doore has a blood-thirsty personality. He is from planet Coola No. 256 (formally planet Beppa). Because the continents of his home planet are surrounded by lava, he has an extremely tough body. He used that physique to become a wrestler in the Galactic Pro Wrestling League. He was undefeated in 300 matches, but he killed all of his opponents during the match.
Doore and the other member of the Armored Squadron are assigned to finding Goku so his master can acquire vengeance in accordance to Frieza's failure. Finding Gohan, he grabs his tail thinking he is Goku. Later, he appears to attack Gohan and this ensues a fight between Piccolo, who soon thereafter kills him with a homing energy blast as Doore tries to chase Gohan.

Apparently, he did not know (or at least forgot) that Planet Namek was destroyed until he met Piccolo, as he asked why Piccolo is not on his homeworld where he belongs, to which Neiz reminds him that Frieza blew it up.

Information from:
http://dragonball.wikia.com/