To live and rise in L.A.

Garth Ancier and Dean Valentine A year ago, Ancier, 38 (prez of the tiny WB TV network), and Valentine, 43 (prez and CEO of the tiny UPN network), were like rulers of some far-flung, forgotten republic. But now fledgling no longer means flailing. Both weblets have carved out a niche — UPN has a strong African-American base thanks to the success of Moesha, while The WB has captivated the hipster set with Buffy the Vampire Slayer.

Polly Anthony Thanks to a management shake-up, Anthony, 43, is now president of two fiefdoms within the Sony Music kingdom — 550 Music and Epic Records. Which means she oversees pop thoroughbreds (Celine Dion, Gloria Estefan) and rock stallions (Oasis, Pearl Jam), making her one of the most powerful women in the music biz.

Stanley Kubrick Sometimes staying underground is the surest way to stay on top. Although the invisible man hasn’t made a movie in 10 years, Kubrick, 68, kept Tom Cruise off the Hollywood job market for a whole year doing endless retakes for Eyes Wide Shut. And when Warner execs want to talk, they have to schlepp to England. Not even the Queen insists on that.

Matthew McConaughey In 1997 this cowboy proved he could stay on the horse. McConaughey, 28, landed a summer hit with Contact while he roped in roles in two of the most sought-after projects in town: Steven Spielberg’s Amistad and Richard Linklater’s The Newton Boys.

Ewan McGregor If this winsome 27-year-old Scot had a shilling for every inch of hype published about him, he’d own more cash than the combined grosses of Trainspotting and Brassed Off. Which might not be saying much, but landing the role of the young Kenobi in the upcoming triad of Star Wars flicks guarantees that McGregor’s career is bound to be much more than ordinary.

David Foster Maybe it’s inevitable that America’s Grammy-stacking maestro of the power ballad (he’s produced Celine Dion, Whitney Houston, and Michael Bolton) would get a hankering for some real power. To that end, Foster, 47, recently signed a contract with Warner honchos Terry Semel and Bob Daly (husband of frequent Foster collaborator Carole Bayer Sager) that makes him a sort of roving chieftain, hunting for divas and deals — from the music labels to HBO to the Warner studio. ”Because You Loved Me,” indeed.

A. Jerrold Perenchio He runs the real fifth network: Univision. The small screen’s numero uno Spanish-language channel reaches a whopping 92 percent of all U.S. Hispanic households. Like a power play out of one of his network’s twisty Mexican soap operas, Perenchio, 66, recently hired former Clinton advisor Henry Cisneros as Univision’s president and COO to help snag advertisers from the Big Four. Forecast for ’98: Muy bueno.

John Wells What Bochco is to cop dramas, ER‘s producer may soon be to medical shows. Wells, 41, is now developing five new dramas for NBC. And if history is any indication (before ER, he worked on China Beach), look for at least one doctor series from the guy who brought blood-and-guts operating rooms into the living room.