in the original boardgame 'Dungeons and Dragons', Vecna used to be wizard until he eventually wished to became a Lich so he could gain immortality, this gave him godhood and is one of the most powerful villains throughout the entire game.
Netflix's show 'Stranger Things' re-imagined the character while adding unique elements like making him a bit more humanized but also making him very similar and faithful to the original character by keeping his Lich-like nature.
A Few years ago, the game 'Dead By Daylight' released a chapter that is a collaboration with the 'Dungeons and Dragons' franchise, this collab included Vecna as the killer. Vecna was voiced by Matthew Mercer, who is a very profilic voice actor(known for roles such as Jotaro Kujo in 'Jojo's Bizzare Adventure' and Levi Ackerman in 'Attack on Titan') and also the owner of the web-series 'Critical Role'(which about voice actors playing 'Dungeons and Dragons').
This year, Netflix announced an animated TV series called 'Stranger Things: Tales from 85', which is a spin-off series based on the 'Stranger Things' show/franchise and will executively produced by the creators of the original show.  It was also revealed that no one from the original 'Stranger Things' show will reprise the roles, confirming that Jamie Cambell Bower(who originally played Vecna in 'Stranger Things') will not come back to voice the character. This opens up the door of the possibility that there could be a chance of Matthew Mercer voicing the 'Stranger Things' iteration of Vecna as he previously voiced the 'Dungeons and Dragons' iteration of the character in the Dead By Daylight collab and how he even owns a show dedicated to voice actors playing 'Dungeons and Dragons'.