Going by Natoma the other day in one of my Rezz alts, I saw this huuuuuuge avatar. There's a running joke about many Second Life residents wanting to be above average in height to the point in reality they'd be seven foot tall basketball players. Some take things a little more, going for eight or nine feet. But this guy was the size of a mountain, even crouched down, towering over the Ivory Tower of Primitives. He was well over a hundred meters in height.
His name was Fop (Kingforri Resident). As it turned out, I'd seen him once before, at the celebration of the 20th anniversary of Natoma's "The Man" statue. But before I could message him, he was gone.
Such avatars are impressive, but highly impractical. Without chat extenders, you can't talk to anyone. You can't really interact with anyone. So most likely Fop only appears like this once in a while. So outside the Fantasy Faire, it's rare you'll encounter a mega-macro avatar like this.