The Mind Stone was an incredibly powerful and ancient stone capable of manipulating minds. An Infinity Stone, various individuals and organizations have possessed it, including Loki, Hydra, Ultron, Vision, and Thanos.
The first known person to possess the Mind Stone was Loki, who was given the Scepter containing the Mind Stone with in it. Thanos entrusted Loki with finding the Tesseract, a containment vessel for the Space Stone. In the aftermath of the Battle of New York, the Mind Stone, along with the Scepter, was placed in S.H.I.E.L.D.'s protection. S.H.I.E.L.D., secretly ran by the Nazi organization Hydra, used the Mind Stone to experiment on Wanda and Pietro Maximoff. The Avengers successfully retrieved the Scepter from a Sokovian Hydra base. Tony Stark experimented on the Mind Stone, creating Ultron. Ultron used the stone to create Vision, who would hold onto the stone until the Battle of Wakanda, where Thanos would extract the stone from Vision's head, completing his collection of Infinity Stones. The Mind Stone was ultimately destroyed by Thanos in the wake of the Snap.