Unknown

Template:Wiktionary The term Unknown is used in a number of known contexts:

the unknowns of an equation are the quantities (or variables) which may be solved for.

To indicate the lack of knowledge, such as the list of unsolved problems, unsolved problems in physics or the unknown unknown
To refer to anonymity
Unknown (magazine) is the title of a fantasy magazine published from 1939-1943.
Unknown is the final boss and last time-released character of Tekken Tag Tournament.
Unknown is a 2006 movie
Unown is the name of a Pokémon breed.