The design team can help you create one.
Go grab a photo of yourself (preferably in a high resolution), upload it somewhere, and create a new ticket at the design team’s Trac repository. (You’ll need to be logged in with your FAS account to create a ticket. The login link is in the upper right-hand side of the page.)
There has been a lot of people on Planet recently without a hackergotchi—just a face. We’ll help you change that. :)