Most wrestlers dubbed the "world's strongest man" over the years haven't really had a legitimate claim to the title. Very strong men, no doubt, and some, like Ken Patera, had very impressive credentials, but nothing that would make them the clear strongest man in the world.
Mark Henry, on the other hand, may very well be the strongest man ever to walk the planet, not just the strongest man in the world for the past 20 years. While some athletes have excelled in powerlifting, Olympic lifting or strongman competitions, Henry has proven himself to be world class in all three.
Henry started in powerlifting before moving to Olympic lifting, where he set four national high school records within eight months. When he was being hyped up as an Olympic hopeful, he set the record for the combination totals of the five lifts in the two sports.
While he didn't medal in the 1992 or 1996 Summer Olympics, he won a silver medal in the 1995 Pan American Games. After the 1996 Olympics, he went into pro wrestling with WWE.
Five years later, he took time off the prepare for the first annual Arnold Strongman Classic, a "world's strongest man" type competition held as part of one of Arnold Schwarzenegger's expos in February of 2002. Competing against world class competitors (many of whom had also been finalists in the more well-known Met-Rx sponsored World's Strongest Man competition that airs on ESPN), Henry came in first place, winning $10,000 and a Hummer that he still drives today.
Henry was also the first man to cleanly lift the infamous 172-plus pound Thomas Inch Dumbbell over his head. This specific dumbbell is so hard to handle because the diameter of the handle is almost two and a half inches.
Mark Henry may not be the best powerlifter, Olympic lifter or even strongman competitor ever, but he's excelled at all three sports at a level that hasn't been equaled. As raw far strength goes, Henry may have no equal.
Speaking of which...