The images were posted by a user by the name of BlackwatchFiles, who is allegedly a developer at Blizzard. The leak contains a drawing and some renderings of the character who will apparently be known as Psyren. According to the character’s biography, Psyren is apparently a former member of Blackwatch and is a student of Overwatch’s Reaper.
While it does seem like a very extensive leak, there are many who have expressed their skepticism about the authenticity of the leak. For starters it does seem a bit too soon to be getting a new hero, especially since usually the wait in between releases is a few months, and with Doomfist being released last week, if Blizzard has a new hero then chances are we might only be seeing it towards the end of the year.
Secondly some have pointed out that this hero seems to lack a proper 3D model of the character, and the artwork certainly seems more like what a fan would draw as opposed to what Blizzard’s artists would draw, so while we can’t say with 100% certainty that this leak is fake, you should probably approach it with a healthy dose of skepticism for now.