Muhammad Ali is the only fighter to win the linear heavyweight title three times, but others who won (at leaast) partial titles at least 3 times include:
evander holyfield (4) two linear titles and two partial belts
vitali klitschko (3) one linear belt
mike tyson
lennux lewis
it is between light-heavy weight and heavy weight (between 176-200lbs)
Buster Douglas
Between 205-265 pounds.
Muhammed Ali
Jack Johnson was the first black heavy weight champion of the world.
World Heavy weight championship
That he is the heavy weight championship
Mark henry
Shaba Edwards
theofilo stevenson