Answer You have to know what dates you're interested in. Dollar coins have been issued on and off since 1794.
To give a rough overview:
90% silver dollars 1794-1935 - various images of Miss Liberty
Dollar coins issued since 1971 are not made of silver
1971-1978 - President Eisenhower (metal: cupronickel "sandwich")
1979-81, 1999 - Susan B. Anthony (again, "sandwich")
2000-present, regular issue: Sacagawea (metal: manganese-brass)
2007-present, Presidential series: Each U.S. president's image appears for 3 months. The series is expected to end around 2016, depending on how many former presidents are alive at that time.
Also, since 1982 there have been various "Commemorative" Dollar coins minted with a variety of face images but these are only sold to collectors and do not circulate.
Currently John Kennedy id on the US half dollar.
Susan B. Anthony, thus the coin is name the Susan B. Anthony dollar.
George Washington
That depends on which dollar coin you mean, 4 different series are in circulation today.
In the year 2000, the US created a 1 dollar coin with a picture of Sacajawea.
Miss Liberty
President William McKinley
It is not George Washington. He is on the US 1-dollar cotton bill.
Salmon P Chase
The US $50 bill shows a picture of President Ulysses S. Grant.
Benjamin Franklin is on the US $50 bill.
President Thomas Jefferson.