100 Trillion Dollars, Zimbabwe

100 Trillion dollar (100 followed by 12 zeroes) banknote of Zimbabwe (formerly Rhodesia), printed in 2008 during the hyperinflation phase in that country. In the late 1990s, the government of Zimbabwe had started expropriating properties of white farmers - many farms were given to loyalists of then president Robert Mugabe. Agricultural production and the economy collapsed as a result - and the government started printing more money to meet its expenses - causing hyperinflation. This note was worth less than 1 US dollar at the time it was printed, and quickly became worthless. It holds the record for the largest number of zeroes to be printed on a banknote. 

Read more about this note here