Citigroup's former chairman and CEO—and one of the titans you can blame for the financial implosion—Weill now soothes his conscience attending to various philanthropic pursuits.

Born and raised in Bensonhurst, Sanford "Sandy" Weill started out as an engineering student at Cornell, but switched to government after nearly flunking out. He managed to graduate, though, and in 1955 he moved to New York, landing at Bear Stearns as a runner and a few years later moving up to broker with just two clients (his mother and a former boyfriend of his wife). Needless to say, things soon picked up. In 1960, Weill went into business on his own, teaming up with partners Roger Berlind, Arthur Carter (and, later, Arthur Levitt). The endeavor succeeded quickly thanks to acquisition-happy Weill, who engineered more than a dozen deals in the 1960s and '70s to create the powerhouse Shearson Loeb Rhodes. In 1981, Weill cashed out, offloading the firm to American Express for $900 million. A power struggle with Amex's James Robinson forced Weill to exit soon after. He started over again with $7 million of his own money, and took over a troubled financial services company called Commercial Credit. Weill proceeded to build yet another financial conglomerate, acquiring nearly a dozen companies over the course of a decade, including Travelers Insurance and Salomon Bros. In 1998, he formed Citigroup via a $78 billion merger with Citicorp.

Weill transformed the rules of the banking game: He helped demolish the Depression-era Glass-Steagall Act that had separated investment and commercial banking, and pioneered the notion that consumers would purchase all of their financial services from a single provider-possibly the height of his professional glory. But his inability to structure his succession cost him his legacy. Critics slammed Weill for leaving his successors with an "unstable" company, a notion he denies. What's undeniable: Citibank required a colossal $45 billion government bailout—stocks plummeted from over $48 per share to $1 after the "supermarket style" bank failed to weather the financial implosion.

Weill has pursued philanthropy as energetically as he pursued empire building over the past few years. He and his wife have funded various artistic institutions around town (reflected by the numerous facilities named in their honor) but Weill's largest gifts to date have been directed to Cornell's medical school and New York Hospital. Now named the Weill Cornell Medical College, the couple has donated an extraordinary $500 million to the center since the late 1990s, including a record-setting $250 million donation in 2007.

Weill is married to Joan Mosher Weill, who's currently chair of the board of the Alvin Ailey American Dance Foundation. The couple has two adult children, Marc Weill and Jessica Weill Bibliowicz. In 2007, Weill paid $42.4 million for a penthouse at 15 Central Park West. The 6,744-square-foot apartment, which has more than 2,000 square feet of terraces, is located on the 20th floor of the "Tower" building. The couple's new neighbors in the building include Dan Loeb, Bob Costas, Denzel Washington, Sting, Dan Och, and Arthur and William Zeckendorf. The Weills also have a weekend home in the Adirondacks.

Both of Weill's children once held senior positions at Citi. (Indeed one of the reasons Jamie Dimon was forced out of Citi was because of his reluctance to promote Jessica Weill as quickly as her father would have liked.) Jessica currently serves as CEO of National Financial Partners. Marc resigned from Citi following a trip to rehab for a cocaine addiction and a widely-reported affair with an adult film actress.

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