AGE: 65
OCCUPATION: U.S. Secretary of Defense
PREVIOUS APPEARANCES ON THE TIME 100: 1
PRO: Obama's decision to keep him on the job allows Gates to oversee the gradual withdrawal from Iraq. And he'll play a key role in determining the next steps in Afghanistan.
CON: The U.S. strategy in Iraq — which requires a shift from occupation to peacekeeping, all by the end of 2011 — is daunting. And war fatigue may make future efforts in Afghanistan a tough sell with both Congress and the public.