In OS X it is easy to create as many user accounts as you need. It’s definitely useful being able to have an account for each family member, or an account just for troubleshooting. However, this also leads to an extremely long list on the login window, and an annoying scroll bar down the side.
If you are running Tiger, hiding user accounts that you rarely use is simple. Firstly, go to the Accounts pane in System Preferences, and find the “short name” of each user you want to hide. Once you have these, open up Terminal (Applications/Utilities) and enter the following:
sudo defaults write /Library/Preferences/com.apple.loginwindow HiddenUsersList -array-add shortname1 shortname2 shortname3
Obviously shortname1, 2 and 3 will be replaced with the short names of the user accounts you wish to hide. You can hide as many as you like, just separate each with a space.
To make a hidden name appear again, type the command with no names in it, therefore resetting the list of hidden users.
sudo defaults write /Library/Preferences/com.apple.loginwindow HiddenUsersList -array-add
Notice that doing this adds an extra option to your login window – “Other…” When you select this, you will be presented with text boxes to enter a username and password.