NOS-4-A2 is a vampiric robot who feeds on energy, whether electrical, nuclear, or any substance that makes machines run.
He was created by Emperor Zurg for the purpose of capturing Star Command and destroying it from the inside out...though after that, he became his own villain and even betrayed Zurg.
NOS-4-A2's name is a play on the word "nosferatu", which is the original term for the vampire race.
NOS-4A2 joins up with Eobard's Syndicate through Toffee at some point in the story and serves as of of The Reverse Flash's Main Allies. He is released by Toffee and is sicced by him to eat Bender which he nearly does before Slade and Harry Wells Resuce him and afterwards he and Mandarin make their allegiance to him.
When The Flying Dutchman manages to bring his ghost ship up to take the team to where Toffee is currently residing. Toffee has expected their arrival and this is when Celes approachs him and threatens him to send Buu back to his timeline. Toffee just sics NOS-4A2 on her and Mandarin joins with Leonard and Lisa working against them both with their guns respectively. When Grovyle and Kyle find the 2nd time gear NOS-4A2 emerges out of the shadows and tries to bite Grovyle with Kyle planning to attack him where Mandarin ambushes him and grabs him with Toffee emerging there congratulating them for finding the Time Gear and that using them was the key. Toffee takes the Gear for himself and searches Grovyle's pocket taking the 2nd one.
As Toffee, Mandarin and NOS-4A2 go together they take the time gears and Toffee presents them to Thawne. Thawne pleased with this and speeds off and puts them back in the base, deciding to keep Grovyle from this. Wally, Nate and Amaya wake up and see Grovyle and Kyle and ask what happened, Kyle reveals that the legion ambushed them and stole their Gears from the two when they went looking for him. NOS-4A2 emerges to attack again with Amaya and Kyle deciding to fight the vampire
NOS 4A2 deals with Kyle and Amaya. And they are really bringing the smack on NOS-4A2, it doesn't help that he is in the light so he lures them into the cave and gets an equal footing with Amaya who summons her bird totem to use to fight evenly with Kyle using magic on occasion to blind him through light to let Amaya keep hitting him. NoS4-A2 zaps Kyle knocking him over and then grabs Amaya content to bite her though Amaya uses her gorilla totem to smack NOS-4A2. Seeing no more point in the fight he retreats. Then Dawnbeth shows up and her powers to trap NOS4a2 after they leave and interrogates him about the Time Gears. NOS-4a2 reveals that Toffee took them for the legion and that he's using them for himself, Dawnbeth lets him go, but puts a device on the energy vampire's back. He is then sent by Toffee to do a mission.
NOS-4A2 continues to serve Toffee and Thawne working to get the spear where he has no real reason for it much like Mandarin, Toffee's other chief follower. NOS-4A2 tells Toffee that he seeked out their target and he succeeded in their goal. He also kills the Teen Titans Go other than Starfire with Mandarin and Toffee when they discover what the 3 is up to. He kills Cyborg specifically using his machinery to drain him dry. NOS-4A2 continues to be a presence and pain to the heroes and eventually when the villains get the spear, NOS-4A2 gets back to Toffee and works on their plan to emerge as the head of the legion for Toffee.
accomplish Toffee's plans. When confronted about Thawne, He and Toffee basically state that Thawne was killed by Bender and Deathstroke to rally them behind Toffee. He, Rodney, Mandarin, Toffee and Marie meet up with Bill who opens the portal to his interdimensional friends. Cipher tells NOS-4A2 and Toffee they he will reward them big for their hard work, offering them a castle. Toffee agrees and NOS-4A2 goes with Madnarin takes over the Magic Kingdom of Disney while Toffee goes through and throws The Disney Head out of the window to his death while Bill unleashes Wierdmageon over the many universes with Marie and NOS-4A2 presents Toffee with his seat at the throne
The Villains all find out about the heroes traveling to Mewni, and He questions how Toffee will manage to conquer Mewni, and all that. Toffee mentions that he will build an army of monsters under his rule to do just that. Marie reminds them that they already are a small army, NOS-4A2 agrees, but believes there might be more they need to do. NOS-4A2 arrives at Bill Cipher's pyramid castle telling him of Toffee's desire to take out the power of Mewni and that they need his help. Bill Cipher gives NOS-4A2 a magic amulet to hand to Toffee to use in his conquest, Toffee then approaches Cipher the Ford Stature upon his request since Cipher knows that they need info on the Spear of Destiny as Toffee and Cipher can't use it.
NOS-4A2 with Rodney and Marie attacks Mewni as the leader of the invasion against Mewni. He avoids attacking most of the heroes, though tries to drain Bender again though Bender gets him off his neck. NOS-4A2 paralyzes Moon upon entry so Toffee can slaughter the magic comission, which he does with ease, and then when he realizes Moon is unparalyzed, he leaves to get Rodney and Marie.
NOS-4A2 then feeds on more power as Toffee and Bill discuss how to get the spear from the heroes before leaving to feed on more of Toffee's machines which Rodney points out is wasterful. NOS-4A2 then acts as one of the final members to be battled, which is where he resurrects robot zombies to do his bidding and has them attack the heroes, he has the upperhand until the combined forces of Luna and Lucy Loud defeat NOS-4A2 by blasting him with music and Lucy hammering a stake through NOS-4A2 with a bomb Mike and Gus placed on there to explode NOS-4A2 to pieces