How to get a list of MySQL User Accounts

I'm using the MySQL command line utility and can navigate through a database. Now I need to see a list of user accounts. How can I do this?
I'm using MySQL version 5.4.1.


Answer : 

Use this query:
SELECT User FROM mysql.user;
Which will output a table like this:
+-------+
| User  |
+-------+
| root  |
+-------+
| user2 |
+-------+
As Matthew Scharley points out in the comments on this answer, you can group by the User column if you'd only like to see unique usernames.