Acronym for Eric Steven Raymond.
- The community has a tradition of tri-letterizing its heroes - I suppose that began with Stallman, already a hero when I was a fledgling progammer in the early 1980s, who was generally known as RMS even then. LinusTorvalds is just "Linus", perhaps because (unlike "Richard" or "Eric") one can refer to him by simply first name with very little risk of aliasing problems.
I think I started to be routinely triletterized into ESR around 1998 on SlashDot; that was a few months after the fame thing started to kick in seriously. It's at best a mixed blessing. Fame is tactically useful, but the pressures and expectations that go with it can be nasty stuff.