The Macaca Nigra self-portrait is a fantastic selfie taken by a monkey that went viral. It is in public domain as a photograph taken by a monkey is unprotected intellectual property.
For fun, the background was removed to create a template for other humorous photos.
The original file can be found at https://commons.wikimedia.org/wiki/File:Macaca_nigra_self-portrait.jpg.
Templates with transparent backgrounds are available as an .xcf file or .png file