Don't know if anyone in this thread collect Enterbay's Shaq O'Neal,
he is the biggest "human" character made in 1/6 in my impression.
Are Uruk Hais taller than Shaq?
Maybe the Berserkers were supposed to be around that tall, but the regular Uruk-Hai were just above average human height.
Lawrence Makoare, who played Lurtz, is 6'4" (just about the same height as Christopher Lee, as seen in the "Whom do you serve?" scene). Lurtz was slightly taller than the other Uruk scouts, however, who in turn were supposedly slightly bigger than the mass-produced Uruks who attacked Helm's Deep.
[Dwayne "the Rock" Johnson (Hot Toys GI Joe Roadblock), who is 6'5", is probably a better model to base Lurtz off of than Shaq.]
Nathaniel Lees, who played Ugluk, is 6'1". The other named Uruk Hai (Lugdush, Mauhur) were played by actors who were 6' or just above.
It wasn't so much the case that the Uruk-Hai were so tall as it was that they had were man-tall, had man-like proportions, and stood upright, while most of the other Orcs were bow-legged, long-armed, and hunched-over "knuckle-draggers" like Grishnakh and Gorbag.