From The United States Department of the Treasury's website:
"As with our nation's coinage, the Secretary of the Treasury usually selects the designs shown on United States currency. Unless specified by an Act of Congress, the Secretary generally has the final approval. This is done with the advice of Bureau of Engraving and Printing (BEP) officials. In addition, the Commission on Fine Arts reviews all of the designs.
The law prohibits portraits of living persons from appearing on Government Securities. Therefore, the portraits on our currency notes are of deceased persons whose places in history the American people know well.
The basic face and back designs of all denominations of our paper currency in circulation today were selected in 1928, although they were modified to improve security against counterfeiting starting in 1996. A committee appointed to study such matters made those choices. The only exception is the reverse design of the one-dollar bill. Unfortunately, however, our records do not suggest why certain Presidents and statesmen were chosen for specific denominations."
Note that these regulations do NOT require that only presidents appear on US bills; the only restriction is that no living person can be shown. In the past many other individuals including inventors, Native American leaders, cabinet members and even First Lady Martha Washington have been depicted.
United States currency notes now in production bear the following portraits:
There are also several denominations of currency notes that are no longer produced. These include:
Three of the above were never President of the US:
Ben Franklin! These $100.00 Bills are affectionately know as "Benjamin's"!!
President George Washington
If you mean whose PORTRAIT is on the bill, the Series 1928 and 1934 bills carried a picture of President William McKinley. Those were the last $500 bills printed in the US.
== == George Washington's picture is on the $1 bill. His name is right there in the caption underneath his portrait, the same as on all U.S. bills.
A portrait of Alexander Hamilton, the first Secretary of the Treasury, has appeared on all US $10 bills since 1928.
There have been hundreds of fake 3 dollar bills with different portraits- and to the best of my knowledge, one REAL series of $3 bills. The REAL bills were bank notes issued by one bank. The St. Nicholas Savings Bank of New York. Yep- the REAL 3 dollar bills had a portrait of Santa Claus- also known as St. Nicholas.
President Grant.
Ulysses S. Grant.
Benjamin Franklin
The portrait of the first President of the United States of America, George Washington, appears on the front of the US $1 Dollar note.
Thomas Jefferson, the 3rd president.
President Ulysses S. Grant