umbraco was founded and is owned by Niels Hartvig, but is made possible by loads of individuals helping out and the core team who's doing the development.
Niels Hartvig, Founder & architect
As the original brain behind umbraco, I'm in charge of development and application/experience design. My primary roles in the project are the contentious development of the umbraco platform and thinking about how umbraco should work and act in the future.
You can read my thoughts at my weblog
hartvig.com
MVPs 2008/2009 (Most Valued Persons):
Core Team
The full list of people in the core team is available at CodePlex - our development platform.