Richard Holbrooke, US special envoy for Afghanistan and Pakistan, died on Monday, after undergoing surgery to repair a torn aorta. He was in critical condition since Saturday, the State Department said. US President Barack Obama, paying tribute to him, said that Holbrooke was simply one of the giants of American diplomacy. Holbrooke, whose forceful style earned him nicknames such as "The Bulldozer" and "Raging Bull," was admitted to the hospital on Friday after becoming ill at the State Department.