Myths that, rather than having been "
organically grown" back in pre- and early history, are
fabrications of recent vintage. Lovecraft's
Cthulhu mythos constitutes a body of
fictitious myths, as do the elaborate fictitious
theologies and
metaphysics of
the AD&D universe,
the planes of Glorantha,
Marvel universe,
Star Trek, or any other capitalized
fictitious universe out there.
History is not
myth, but a
fictitious history can be interwoven with myth (e.g. Julian May's
Saga of Pliocene Exile).