XU
- Snippet from Wikipedia: XU
XU (X for "unknown" and U for "undercover agent") was a clandestine intelligence organisation working on behalf of Allied powers in occupied Norway during World War II. Though its work proved invaluable for operations against German operations in Norway, most of its operations, organization, etc., were kept secret until 1988.
The name of the organization may have derived from Lauritz Sand, one of the founding members, who had previously worked for British intelligence in the Dutch East Indies and coined the name XU, X for "unknown" and U for "undercover agent" for his group.