WoW, Starcraft, and Diablo themes are coming to Overwatch!
https://i.imgur.com/IPaQkaw.jpg
They will be added to the base loot box. No event or anything needed to get them.
Screencaps of all the skins from the Blizzcon stream:
Torb - https://i.imgur.com/dqtOyAh.jpg
Widowmaker - https://i.imgur.com/a7ZLoAs.jpg
Doomfist - https://i.imgur.com/fs9siyi.jpg
Orisa - https://i.imgur.com/xvhVUoM.jpg
Zarya - https://i.imgur.com/0pqWELp.jpg
Roadhog - https://i.imgur.com/bhjHuiY.jpg
Reinhardt - https://i.imgur.com/zSBpQqD.jpg
Mei - https://i.imgur.com/uKjZ8Fi.jpg
Whipped Cream Gun! - https://i.imgur.com/GHXZzBI.jpg