As ABED pointed out Piroshki is based upon Big Van Vader...
However, Toriyama has a character in the preliminaries of the 22nd Tenkaichi Budokai who resembles Andre the Giant (see page 91 of Dragon Ball Viz Big Edition volume 4). The anime took it a step further having Yamcha give some background on the guy, naming him as "Anton the Great" noting that he is/was a Pro-Wrestler. It could be debated whether or not Toriyama based him off Andre the Giant but there's no doubt that's what the anime staff were going for. Other than his face he looks and dresses like a 1970s/early 80's Andre so it's entirely plausible.
Dragon Ball wikia claims he's called "Gregor" (where that comes from I don't know) and that he first appeared in Dragon Ball Movie 3 which is not true at all as the dates don't add up.
The big guy Gohan fights in DBZ Movie 9 appears to be based on Stan Hansen, who's considered the most successful "gaijin" (foreigner) in the history of Japanese Pro-Wrestling.
There's more that I'm forgetting about, the most obvious one I can think of is that there was someone in the anime with Hulk Hogan's head in a group shot of the fighters during one of the Budokai preliminaries - I don't remember which one it was off the top of my head.
