The Red Devil is a Hard Mode enemy found in The Underworld that appears after at least one mechanical boss has been defeated. However, in console version, there is a bug where they spawn in a pre-Hardmode world after at least one mechanical boss has been defeated. It attacks by summoning up to five tridents that fly in a straight line, much like Demon's projectiles. The Red Devil is the Hard Mode version of a Demon.
- Death comes easily if all five tridents hit the player, even if they are wearing a high tier armor like Hallowed Armor. The tridents can easily do over 100 damage, even while having around 50 Defense.
- Similar to the Demon, the attack cannot be interrupted by damaging the Red Devil. Players may be surprised by this during their first encounter.
- Now has its own exclusive banner.
- Now has a chance to drop a Demon Banner.
- Added to the game.