Galaxy And Beyond

Conceptually reconfiguring several works by James Blish:

(i) "The Writing Of The Rat" (a single short story);
(ii) The Haertel History (Welcome To Mars and the Galactic Cluster trilogy);
(iii) The Heart Stars (the Jack Loftus novels);
(iv) The Seedling Stars;
(v) Cities In Flight;
(vi) The Quincunx History (The Quincunx Of Time, "A Style In Treason" and Midsummer Century).

(i)-(iii) end with humanity beginning to engage in conflict with a powerful race at the galactic centre.
In (iv), humanity has forestalled such a conflict by early colonization of the entire galaxy with Adapted Men.
In (v) and (vi), human activity becomes intergalactic.

(iii) is also intergalactic in scope because the star-dwelling "Angels" communicate across the universe and interacted with civilizations in ten other galaxies before the Milky Way.

Space travel in sf is usually within the Solar System or within the galaxy but does not often go further. Exceptions are these works by Blish, two novels by Poul Anderson and Into Deepest Space by Fred and Geoffrey Hoyle.