El Jabato

"In the 1950s and 1960s, the most popular comic books in Spain weren't about Superman and Spiderman - they told of the adventures of El Jabato, an imaginary ancient Iberian hero who fought against the Roman oppressors."
-Yuval Noah Harari, Sapiens: A Brief History of Mankind (London, 2014), Chapter 11, p. 211.

An addendum relevant to Poul Anderson Appreciation: Ancient anti-Roman freedom fighters, including the fictional individual, El Jabato, and the inhabitants of the historical town of Numantia, are regarded in Spain as symbols of national independence. The Numantians were defeated by the Roman general, Scipio Aemilianus, who had previously levelled Carthage. Delenda Est Carthago. All history is one story.

The League IV

JSA: the original superhero team.
JLA: a revival.
Infinity Inc: the JSA's children.
Titans: the JLA's junior partners.
Freedom Fighters: a team encountered during a JLA-JSA team-up.
Helix: JSA-inspired opponents of II.
All Star Squadron: all the WWII heroes.
Young All-Stars: post-Crisis replacements of the main JSAers.
Young Allies: WWII allies of the Young All-Stars.

All superheroes, and therefore all superhero teams, are successors of Superman. The Legion of Superheroes are also successors of Superboy, who was "Superman as a Boy."

The League III

The Justice League was a revival of the Justice Society, the first super-hero team, which started in 1940 and had several off-shoots:

the Justice League
the Teen Titans
the Freedom Fighters
Infinity Inc
Helix
the All Star Squadron
the Young All-Stars
the Young Allies

More than you might think.