The US $10 Dollar and US $100 Dollar banknotes are the only 2 bills which do not feature a President of the United States on the front. The $10 bill features the first US Secretary of the Treasury, Alexander Hamilton (1755 - 1804)

USA (2004) 10 Dollar - portrait of Alexander Hamilton

and the $100 features Benjamin Franklin (1706 - 1790) one of the founding fathers of USA. Alexander Hamilton is also the only person featured on US banknotes not born in the United States. He was from West Indies. Benjamin Franklin was a noted polymath, leading author and printer,....

USA (2004) 100 Dollar - portrait of Benjamin Franklin

satirist, political theorist, politician, scientist, inventor, civic activist, statesman and diplomat. As a scientist he was a major figure in the Enlightenment and the history of physics for his discoveries and theories regarding electricity.

Source: Wikipedia's articles here and here