It depends on what you mean by dollar coin because there have been a lot of them. If you have a presidential dollar (it has a gold color, but contains no real gold) then it could be any president up to Lincoln (I don't believe they have minted Lincoln's coin quite yet as of this writing), if it is a Native American woman, it would be Sacajawea, if it is one of the large dollars and a real person, that would be Dwight Eisenhower, a former US president. If you have a small dollar coin that is very similar in color and size to a quarter, that is Susan B Anthony. If you have an older US coin, it would be some personification of the goddess Liberty.
The 1891 Morgan Silver Dollar can be seen by using the link to a picture of this coin.
Susan B. Anthony
President Dwight D. Eisenhower
George Washington. From 1928 to 1934, the one dollar bill was actually known as a Silver Certificate.
$1 coins minted from 1971 to 1978 carried a picture of President Eisenhower
Susan B. Anthony, thus the coin is name the Susan B. Anthony dollar.
See link to Australian one-dollar coin
Susan B. Anthony
The 1891 Morgan Silver Dollar can be seen by using the link to a picture of this coin.
There's one at the Related Link.
Susan B. Anthony
Which one? please be more specific and post new question
The one dollar Canadian coin is called a loonie or loony because the coin has a loon picture on one side. The toonie or toony is worth two lonnies because it is a two dollar coin.
President Dwight D. Eisenhower
Which one? Which date? Post new question with more information.
George Washington. From 1928 to 1934, the one dollar bill was actually known as a Silver Certificate.
$1 coins minted from 1971 to 1978 carried a picture of President Eisenhower