Who
A former partner at Goldman Sachs and now a major art dealer and advisor, Mnuchin is co-owner of L&M Arts. His partner in the gallery/advisory firm is Dominique Lévy.

Backstory
Mnuchin spent 33 years at Goldman Sachs before turning to his full attention to the art trade. A Yale grad, he joined the bank in 1957, became a partner a decade later, and headed up the trading and arbitrage division during the 1970s, making his reputation by pioneering the now-common practice of "block trading" under the tutelage of legendary Goldman chief Gus Levy. After serving as a member of the management committee in the 1980s (and after mentoring a handful of future Goldman stars like Bob Rubin and Jon Corzine) Mnuchin retired in 1994.

He soon turned his attention to art, a passion he'd nursed since the '70s when he'd begun to accumulate a collection of pieces by artists like Jackson Pollock, Willem de Kooning and Mark Rothko. In the mid-'90s, Mnuchin teamed up with Los Angeles dealer James Corcoran to start C&M Arts on the bottom two floors of his five-story townhouse on East 78th Street. Corcoran left the firm, and C&M became L&M in 2005 when Mnuchin joined up with Christie's alum Dominique Lévy.

Of note
Mnuchin and Lévy are an unusual duo—she's youthful and stylish, he's partial to rumpled suits and thick glasses. But L&M has established itself as one of the most formidable dealmakers on the contemporary art scene, buying and selling works on behalf of a slew of high-powered clients. A fixture at every major auction where he can be found kibitzing with other art insiders and yapping into his cell phone, Mnuchin plays two roles in the marketplace: He collects for himself and secures work for clients, many of whom have earned their riches, like Mnuchin, on Wall Street—such as Steve Cohen, the billionaire founder of SAC Capital.

Rumored to be one of the easiest of the new batch of contemporary dealers for market newbies to deal with, it certainly helps that Mnuchin doesn't charge a commission—he considers it a "service"—although given just how much he has sitting in the bank, he hardly needs to. But Mnuchin and Lévy's deep pocketed clients have turned them into exceedingly aggressive players in recent years. At one Sotheby's auction in 2006, L&M spent $34.9 million to acquire five works of art, including pieces by Willem de Kooning, Roy Lichtenstein, Christopher Wool, and Jeff Koons.

On the side
Until 2007, Mnuchin and his wife were the owners of the Mayflower Inn, an upscale B&B located in Washington, Conn. Mnuchin's wife, Adriana, is co-founder of the Shakespeare Society and remains on the board of the non-profit.

Family ties
It's quite the power family. Bob has two sons with his now-deceased first wife, Elaine Terner Cooper: Alan Mnuchin is a former banker at Bear Stearns and Lehman Bros. who now runs his own advisory firm, AGM Partners, which has represented Edgar Bronfman Jr.; Steven Mnuchin is a former Goldman Sachs partner who worked with Eddie Lampert at his hedge fund ESL and now runs Dune Capital, a fund financed by George Soros. Art is an abiding passion for the entire family: Steve and his wife Heather, and Alan and his wife Kim, are all avid collectors and art fundraisers.

Personal
Mnuchin's second wife, Adriana, is an entrepreneur who founded Tennis Lady, a chain of 21 tennis-fashion stores in the 1970s, and Cashmere-Cashmere, a chain of cashmere stores in the 1980s. The couple has a daughter named Valerie. They live in a full-floor co-op on Fifth Avenue that they purchased for $20 million in 2008. (Barbara Walters is a neighbor in the building.) They spend weekends at their house in Washington, Conn.