Wells' Time Traveler;
two versions of the Doctor;
Poul Anderson's diverse time travelers.
These might be "true myths," in Olaf Stapledon's sense of that phrase:
Wells' 802,701 A.D., followed by his Further Vision;
a visit to the asteroidal remnants of Earth in the Doctor's TARDIS;
interstellar civilizations where the Time Patrol operates openly and, later, the Danellian Era;
the Star Masters period in There Will Be Time;
the time wardens period in The Corridors Of Time;
the Second Empire and the later "gods" in "Flight to Forever";
the later civilizations in several spiral arms in the Technic History;
the multi-species civilization at the Galactic Center in "The Chapter Ends";
post-organic intelligences spreading through and beyond the galaxy in Genesis;
downloaded consciousnesses endlessly reembodied on terraformed planets in the Harvest of Stars tetralogy;
That is a considerable number of myths from Poul Anderson.
Addendum: See also the conclusions of War Of The Gods and Starfarers here and here.