Rep. Rahm Emaneul (D-Ill.), recently selected as chief of staff to President-elect Barack Obama, was reportedly the inspiration for Josh Lyman, the deputy chief of staff character played by Bradley Whitford on TV's The West Wing.... while his brother, Ari, an L.A. talent agent, is reportedly the inspiration behind Ari Gold, the character played by Emmy winner Jeremy Piven in HBO's Entourage.

Source: The San Francisco Chronicle
http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/11/07/MN6C13VKH5.DTL&hw=rahm+emanuel&sn=001&sc=1000