Koschei_B
https://event-kosch.dreamwidth.org/1480.html

Archive 81 (Podcast)
Aleister (Archive 81), Michael Waters (Archive 81), Nicholas Waters, Static Man (Archive 81)

Stellar Firma (Podcast)
Bathin (Stellar Firma), David 7 (Stellar Firma), Percy the Clone (Stellar Firma), Trexel Geistman

Hamster & Gretel (Cartoon)
Any (Gretel Grant-Gomez, Hamster (Hamster & Gretel), Hiromi Tanaka, Kevin Grant-Gomez, Winifred "Fred" Grant)

Malevolent (Podcast)
Arthur Lester, John (Malevolent), Kayne (Malevolent), The King in Yellow (Malevolent)

I would absolutely adore any of the prompted characters to be trans in any way, but some ideas:

In Archive 81, my headcanons are - Nicholas Waters is a trans man, Static Man is non-binary, and Michael Waters is agender/gender apathetic
In Hamster & Gretel, my headcanons are - trans girl Gretel and non-binary Fred
In Stellar Firma, David 7 is canonically non-binary, my headcanons are - trans man Trexel, non-binary Percy (implied, but not entirely canon)
In Malevolent, non-binary John would be lovely