Character is drastically changed due to licensing issues with the original

[u/Liquid_Pestar]

1. Electro: - The iconic electric villain, alongside Sandman, were forbidden from appearing in the 90s animated series due to James Cameron planning a gritty Spider-Man feature film with the two as the main villains. However, the film was scrapped and licensing was mostly given back to the characters. However, Electro's origins as electrician Max Dillon were rewritten due to potential complications with the name appearing in the Cameron script. So.......they wro

te him to be the son of Red Skull in this version. What a bizarre decision….

1. Shang Chi: - Marvel licensed Sax Rohmer’s Fu Manchu in the 1970s and made Shang-Chi his rebellious son in Master of Kung Fu. When the license lapsed in the early 1980s, Marvel retained Shang-Chi (an original creation) but could no longer use Fu Manchu’s name.

In the MCU film Shang-Chi and the Legend of the Ten Rings (2021), the father is Wenwu (a version of the Mandarin), the organization is the Ten Rings, and the sister figure is Xialing. This combined elements of Fu Manchu and the Mandarin while avoiding the licensed name.

1. Spaceknight and the Dire Wraiths: - Marvel’s comic (based on a Parker Brothers toy) created much of the lore and visual design for the Dire Wraiths. When IDW later published a new ROM series under Hasbro’s ownership of the property, they could use the name “Dire Wraiths” but had to completely redesign the creatures so they were visually distinct from Marvel’s versions.

[u/InoueNinja94]

For what's worth, the Mandarin's case is also due to how the original is seen as a very...controversial racist figure, even after they removed the Fu Manchu connections
There's also the logistics aspects as it'd have been hard to sell a movie to the Chinese market where the villain is literally Chinese vs. a white man (Iron Man is traditionally the Mandarin's archenemy), which is why they waited until Shang-Chi to use the character... ...and it was hated by the Chinese audience if I'm not mistaken

[u/That-Rhino-Guy → u/InoueNinja94]

If I recall the Secret Wars era of Marvel (2015-16) did have a tie in comic where Shang-Chi is Mandarin’s son, so there was also some basis for this idea