Sledge was a member of the marauding biker gang featured at the end of the movie. It is unclear if Sledge was a leader in the gang but he does seem to have some power as he was able to demand a bike from the gang to try and escape the mall.
Per his name, his weapon of choice is a a sledgehammer, though he does carry a firearm. Sledge appears to be in a click with other members of the gang that includes Blades, Jack, Charlie Moonbaby and possibly The Serape Biker.
Unlike other members of the gang, Sledge did show some concern for fellow gang members. During the uncut version of Dawn of the Dead, he is heard yelling "look out" towards Charlie Moonbaby when zombies are getting too close. He also swung his Sledge hammer at a zombie that was descending upon Charlie Moonbaby after the biker had been shot. This indicates he has sense of camaraderie and his moral compass might not be completely off kilter due to the coming apocalypse.
Sledge met his demise after taking a bullet from Peter Washington and being torn apart by a horde of zombies. Due to the sheer number of zombies in the mail, it is unlikely Sledge reanimated and was most likely completely consumed by the zombies.
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