Smog is a man named Bill Callahan. For some reason or other, he's recently started just using his real name professionally.
I first heard Smog on the High Fidelity soundtrack (I get introduced to lots of new-to-me artists through soundtracks -- I can name 3 people I now love whom I heard first on the Big Lebowski soundtrack), with his song "Cold-Blooded Old Times."
"Vessel In Vain" used to be my favorite Bill Callahan song, until last year when he released Woke On A Whaleheart, which includes the song "Sycamore." Now THAT is my favorite Bill Callahan song. (If anyone asks, I can post that one soon.)
PS -- Sorry for the slack over the last two days. More Stagger Lee tomorrow!