DnD, D&D influenced Stranger Things

The Duffer Brothers have explicitly described D&D as one of the show's major inspirations.

• The kids' party structure → Mike, Dustin, Lucas, Will, etc. each fill different "party" roles.
• The Upside Down adventure structure → essentially treated like a gigantic D&D campaign.
• Monster naming → Demogorgon, Mind Flayer, Vecna.
• Vecna himself → directly borrowed from the D&D villain.
• How the kids understand supernatural events → they use D&D monsters as analogies for things they don't understand.
• Dungeon Master mentality → the Duffers have compared the writers to DMs, throwing increasingly difficult challenges at their characters.
• Character archetypes → the kids' D&D roles reflect their personalities in the real world.

The Duffers actually described Stranger Things as being like a massive D&D campaign where the role-playing takes over their lives.