Ultron Sentries were artificially intelligent robots created and controlled by Ultron. Ultron had the ability to move his consciousness into any of the Ultron Sentries.
Ultron Sentries were glimpsed in a vision by the clairvoyant Inhuman Raina, who witnessed Ultron leading his army of drones against humanity, causing horrific levels of destruction. Raina and Jiaying, to whom Raina relayed the information to, were visibly troubled by the vision.
After Ultron revealed himself to The Avengers in the form of spare parts taken from destroyed Iron Legion drones, which was subsequently destroyed by Thor, Ultron began constructing a new body and an army of sentries out of the unfinished robots Tony Stark found in a hidden sub-level of Hydra's fortress in Sokovia. Ultron acted as a "hive mind" that controlled each sentry drone.
- Wolfgang von Strucker - Developer; deceased.
- Ultron - Creator; deceased.
- Pietro Maximoff - Ally turned enemy; deceased.
- Wanda Maximoff - Ally turned enemy.
- Vision - Enemy.
- The Avengers - Enemies.
- James Rhodes - Enemy.