HOLY SHIT
This will probably not be as impactful to anyone but me, but:
And in 1974, Joe Simon and Jack Kirby — the creators of Captain America — took a spin on reviving the Sandman. This time around, the hero wore a bright red and yellow costume, and prowled the “Dream Stream” in search of rogue nightmares, dispatching them with his magical pouch of dream dust lest they invade the dreams of children.
This Sandman only stuck around for a few issues, but a decade later his story was folded into a story in Wonder Woman. Even later, that story was folded into a story in Infinity Inc., a team book about the grown children of the retired Justice League of Earth 2.
And in that story, Hector Hall — son of Hawkman and Hawkwoman — became trapped in the Dream Stream and took over the duties of the Sandman. Eventually, he brought his wife, Hippolyta “Lyta” Hall — the daughter of Wonder Woman and Steve Trevor — into dreams as well, where the two conceived a child.
These two characters both have their influences on The Sandman. For example, Dream’s black, elongated helm is an interpretation of Dodds’ 1940s gas mask, and the linking of Sandman to actual power over dreams comes from Kirby and Simon.
So: When I was a little kid, my cousin gave me a huge pile of comics when she was moving out to become an adult, and I always remembered just a single issue of them that was, well, Sandman. When Neil Gaiman's Sandman came out, it always was this totally unexplained Mandela effect or self-memory-glitch that I swear I read a pulp-comic issue of it from decades before it was created (very clearly the same, same type of "helm," multiple characters in common, the same).
On this very day one of the great mysteries of my life has been resolved.
Mainly as you said with brute and glob but also how hector hall and lyta hall are seamlessly interwoven into the story and how central lyta halls character becomes.
Another is Wesley dodds and his story (the original 40’s sandman) was integrated as well. It was explained that since Dream was trapped, that the universe tried to find someone to fulfill his role so Wesley Dodds began having dreams subconsciously telling him to do Dreams job. Basically it explains why he existed as the sandman in the 40s within the dc universe.
Characters from the House of Mystery comics actually comprise more of the main characters than you would expect. Lucien, Cain and abel, and even Matthew, Dream’s raven is a character from Swamp Thing who died and is reincarnated as a raven.
Theres alot more but those are the major callbacks off the top of my head. Gaiman really liked putting lesser known dc characters in his story and pressented them in such an original and unique manner that alot of the time you dont even realize they are callbacks.
Holy crap - I read that whole brief summary of the Justice League lore without even connecting it to Lyta Hall and that whole story. You're right, that's a masterpiece. (And, an instructive example of how to make your own excellent stuff without insisting on your own special-snowflake-mode incompatibility with everyone else's stuff.)
Or reboots and bringing dead characters back. Or multiverse and runner travel.