It should be obvious by now that I like them Big.
My favorite character from the Song of Ice and Fire books is Ser Gregor Clegane, and they don't come much bigger than him.
Standing 7 feet 11 inches (one inch under 8 feet) tall, he is known as The Mountain That Rides, and is probably the 'ardest man in Westeros.
,
So what?
I'm not sure. But even that man shouldn't tower over a Space Marine!