Richard Garriott, also known to fans as Lord British (or RG, or LB), is one of the most venerable and influential game designers in computer gaming history. He is responsible for the Ultima series, and founded Origin Systems. The history of Garriott's work is best found elsewhere; here I am just outlining the kind of impact he has had on the computer gaming industry. Richard Garriott recently left Origin (sick of Electronic Arts) now works for NCSoft, a Korean company that develops the MMORPG Lineage: the Blood Pledge. He is rumored to be working on a new original project (formerly called 'X') that will combine the benefits of current MMORPGs and single-player RPGs.

* Rogue and Hack predate it, but weren't ported to the PC until 1984 and weren't really influential until much later.

/msg me if any of this is wrong. I'm basing it mostly on what I know and have heard than facts I can back up here.