The flash V

THE FLASH V

In season 3 the main supervillain is Savitar, he is the god of speed. He is the evil part of Barry Allen who wants to kill Iris West. 

Savitar was created in Flashpoint (a timeline created by Barry when he travels to the past to save his mother). 

Savitar ultimately kills HR who had a technology that could change his face to the one he wanted. 

HR uses it to  Iris, Savitar kills HR and not Iris in the end it is she who kills Savitar. 

 There will also be a ground crossover X in which the components of The flash and themselves will be but in Nazi version.