Mazinger Manga
Manga
I organized this list with the main timeline stuff first, the reboots/remakes second, the spin offs third and the crossovers last.

Manga, 4 vol, 1974
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An alternate version of Great Mazinger with different art

One-shot, ? vol, -
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A little spin-off taking place during Great Mazinger

Manga, 1 vol, 1975
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It incorporates characters from Great Mazinger and Mazinger Z so it’s considered the sequel to Great Mazinger

Manga, 5 vol, 2014
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An autobiographical manga about Go Nagai’s creation of Mazinger Z

Manga, 8 vol, 2012
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The sequel to the retelling

Manga, 1 vol, 2017
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Spin-off that’s a prequel to a Mazinger Z movie

Manga, 4 vol, 2004
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A spin-off that stars some of the female cast of Mazinger Z, Great Mazinger, and Grendizer

Manga, 1 vol, 2013
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Is much like the 2 above manga but goes off the Toei anime version of the shows

Manga, 5 vol, 1975
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Spin-off that has basically nothing to do with Go Nagai’s original work

One-shot, ? vol, 2013
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A crossover between Mazinger Z and the Kekkou Kamen franchise

Manga, 1 vol, 2009
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A crossover between Mazinger Z and the Steel Jeej! franchise

Manga, 3 vol, 2012
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A crossover between Great Mazinger and the Devilman franchise

One-shot, ? vol, 1998
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A crossover between Mazinger Z/Great Mazinger and the Shin Getter Robo franchise

Manga, 1 vol, 2009
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A crossover between Shin Mazinger and the Cutie Honey franchise

Manga, 4 vol, 2004
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A large crossover between Mazinger Z/Grendizer and the Devilman franchise, and the Cutie Honey franchises. The characters take after the 1970s anime versions of each respective franchise.

Manga, 1 vol, 2002
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A large scale crossover between Mazinger Z/Great Mazinger and the Getter Robo/Getter Robo G, Grendizer, and Jeeg! franchises