wikipedia.org is owned by:
Domain name owner details are associated with every domain registration. It may be useful to know who the person or company operating a website or online service is.
Finding the owner details of a domain name is easy, use the whatsmydns.net domain name owner details tool to discover the owner of a website.
Domain name owner details are publicly recorded against any domain name. If the owner details are provided, then they can be retrieved by anyone.
Many domain name owners choose to hide their details due to privacy concerns. Domain privacy, which is sometimes known as whois privacy is a service which allows owners to hide their details. Typically, domain privacy services will offer the ability to forward requests on to the real owner but do not publicly show this information or reveal the owner when requested.
Most domain names can be checked, however in some cases it is unknown for various technical reasons.