The former head of the flagship Guggenheim Museum on Fifth Avenue, Dennison is now an executive at the auction house Sotheby's.

After attending college at Wellesley and interning at the Guggenheim under then-director Thomas Messer one summer, Lisa returned to Brown to earn an M.A. in art history. In 1978 she returned full-time to the Guggenheim, where she quickly navigated her way up the curatorial ladder: In 1985, she earned her first chance to oversee a show, putting together works by nine fledgling American artists; by the 1990s, she was working on some of the Guggenheim's biggest exhibitions and advising art-collecting moguls like Steve Wynn on their multi-million acquisitions. In 2005, with director Thomas Krens' leadership facing increasing criticism, board chairman William Mack stripped him of day-to-day control of the flagship museum and placed Dennison in charge. As director, she spent two years deciding what pieces were to be displayed in the famous Frank Lloyd Wright rotunda (along with chief curator Nancy Spector) and headed up fund-raising efforts.

Dennison has established a rep as both a shrewd curator and an effective money-raiser, and over the years a number of other museums (such as the Los Angeles County Museum of Art) made valiant attempts to lure her away. She resisted all overtures until 2007, when Sotheby's contemporary art chief Tobias Meyer successfully persuaded her to give up the Guggenheim—and the world of nonprofit—for a much more lucrative position at Sotheby's. Dennison now focuses on "international business development" where her job seems to consist of coaxing tycoons to sell their art through Sotheby's or pay the auction house steep fees to advise them on purchases. [Image via Getty]