Ultron is one of the classic nihilistic robot baddies, and a traditional Big Bad for the Avengers. He’s been around since 1968, and has held his rank as a powerful master villain ever since.
Avengers #22 – This Evil Triumphant released by Marvel on November 1, 1999
The Slorenia strikeforce team of Avengers (Black Panther, Captain America, Thor, and Firestar) are being swarmed by hundreds of Ultron robots, and are close to being overwhelmed. Jarvis notices Justice is gone from Avengers Mansion. Ultron is nearly done making the brain imprints of his ‘family’, as the Vision gets free as well as Eric Williams. He frees the other captives as the strikeforce crashes through the door. They swarm Ultron as Justice arrives and gives them Vibranium, which can defeat Ultron. The team regroups as Alkhema is revealed to have all the imprinted brain patterns.