Enter is to entrant as exit is to * [closed]

A person who enters something is called an entrant.

What is a person who exits something called?

Depending on the context, you would specify the person exiting something by the nature of their exit:

For example in a competition:

• "drop-out"
• "loser/defeated"
• "victor"

If talking about an institution:

• "alumnus"

Depending on what you consider a "proper" word, you can also say "exiter" which has at least one precedent:

"High lateral entry is associated with low gross entry and exit rates and patent shares, low relative size (in terms of patents) of exiters (in particular, lateral exiters), and net entrants and exiters."

1999, Alfonso Gambardella, Franco Malerba, The Organization of Economic Innovation in Europe (page 53)