Larry David is hardly a household name. But few households do not know the intimate details of his life, his obsessions, his euphemistic catchphrases (''master of my domain''). He, not Mr. Seinfeld, had the wacky neighbor named Kramer. He once ruined a suede jacket worn for a scary meeting with a girlfriend's father. He was the model for Jason Alexander's portrayal of Jerry's alter ego, George Costanza. And yet, the only on-air exposure his millions of viewers ever got to Mr. David was his uncanny vocal impersonation of George Steinbrenner.

HBO subscribers got a glimpse of him, though, in an hourlong mock documentary, also called ''Curb Your Enthusiasm,'' which the channel has shown every so often since last October. In it, a camera crew purports to follow Mr. David, who is 52, around as he works the comedy club circuit in preparation for a supposed HBO stand-up special. It ends with Larry chickening out of the special. Other characters include his wife and his manager, who happen to hate each other, various alleged HBO executives and cameos by minor celebrities. ''Curb Your Enthusiasm'' was directed by Robert Weide, a documentary filmmaker whose specialty is comedians (most recently Lenny Bruce). The whole thing was a put-on, but seemed so real that a friend of the actress playing Mr. David's wife was offended that she wasn't invited to their wedding.

Imagine ''The Larry Sanders Show'' -- only more so. Coincidentally in sync with ''Survivor'' and the current mania for voyeuristic programming, Mr. David has created a hybrid of extreme reality and extreme comedy. All dialogue is improvised from a loose five-page outline that he has written for each of the 10 episodes of the series. The stand-up scenes and mock-documentary gimmick have been dropped. But it still has the same verite feel. It's deadpan in a way that will certainly appeal to critics if not a mass audience expecting the second coming of ''Seinfeld.'' In some ways ''Curb'' is subtler and more nuanced, but with the same unmistakably Seinfeldian structure of snowballing bad luck. Mr. David's desert island may be Los Angeles, but that doesn't make survival any easier.

''This show is about a guy trying to get through the day with a little dignity attached,'' said Chris Albrecht, HBO's president of original programming. Mr. Albrecht has known Mr. David since the 1970's, when they were both unsuccessful comics at Catch a Rising Star here. ''Larry's an incredible everyman,'' he said. An everyman reported by Forbes magazine to have hit a $242 million jackpot when ''Seinfeld'' was sold into syndication. But unlike Mr. Seinfeld, who collects Porches like baseball cards, Mr. David has never really been able to enjoy his windfall.

''Mostly what it does is make you apologize a lot,'' he said. Unlike the dwarfish, irritable Costanza, Mr. David is a rangy character with a quick smile. He has a penchant for wide-wale cords and untucked shirts. To look at him, you wouldn't know he was loaded, but out here, you never can tell. By the pool of the once-glamorous Roosevelt Hotel on Hollywood Boulevard, he ate his lunch during a break in the incest group scene and subjected himself to questions about the real Larry David. ''I have quite a house,'' he said. ''People come over and I go, 'I know, I'm sorry.' ''