A perennial on this list, Rahm’s most valuable unpaid adviser and confidant (they’re like brothers), a bigtime asset manager ($55 billion under management), and the vice chairman of World Business Chicago (the city’s chief corporate ambassador), Sacks is a bona fide superpower in the worlds of business and politics. He and his wife, Cari, contributed nearly $3 million to the mayor’s last two races, and they recently gave more than $650,000 to the Obama presidential library. Lately, though, Rahm’s critics are asking to know more about the mayor’s dealings with Sacks: After the Tribune’s FOIA request for emails between the two was denied by City Hall just after Rahm’s reelection, the paper filed a lawsuit in September to order the release of the correspondence.