According to Baseball-Reference.com, there have been 10 different Major League Baseball players nicknamed "Wild Bill," from Bill Hutchinson in 1884 to Bill Connolly in 1953.
But there is only one Ed Heusser, "The Wild Elk of the Wasatch."
Heusser pitched for five different teams in the 1930s and 40s, though why he reminded anyone of a wild elk is not clear. (It seems safe to assume "Wasatch" refers to the mountain range in Utah, where Heusser was born). He ended up with 300 walks (compared to 299 Ks), but didn't hit an especially large number of batters or throw that many wild pitches.
I just hope this unsolved nickname doesn't come to haunt me the way that Bristol Robotham Lord's "The Human Eyeball" still does.
NB: Heusser is not to be confused with Pepper Martin, "The Wild Horse of the Osage."