Just for bella
Nico Rosberg - GP2 - 2005
Lewis Hamilton - GP2 - 2006
Nico Hulkenberg - GP2 - 2009 (+2008/09 Asia series)
Sergio Perez GP2 - 2009-10 (+2008/09 Asia series)
Romain Grosjean GP2 - 2008-09, 2010-11
Pastor Maldonado GP2 - 2007-10
Jules Bianchi GP2 - 2009-11
Max Chilton GP2 - 2010-12 (+2009/10 Asia series)
Esteban Gutierrez GP2 - 2011-12
Marcus Ericsson GP2 - 2010-13 (+2009/10 Asia series)
Kamui Kobayashi GP2 - 2008-09
So the 2 standout GP2 graduates are the only graduates to have raced in the series with the GP2-05 chassis. Whilst the Hulk is probably the other standout (and the only other one to have needed just 1 season before they enter F1), the other notable graduates (Perez, Grosjean, Bianchi and Maldonado) all spent more than one season in the series before they got their chance.
Just to help people out, GP2 had new chassis for each of the following seasons: 2005, 2008, 2011