Another speedster they could introduce, one more in the conventional sense (if running at super high speeds can be called conventional) is Savitar. He views his powers as a gift from the Gods, and quickly develops a cult following, while testing and pushing his abilities further than The Flash does. He can create a force field around himself, and also give speed to other people and objects. If the show wants to expand on the Speed Force mythos then hed be a character to include, as hes very connected to it, and before he was Savitar he was a test pilot, getting his powers when lightning struck the plane he was flying. Theyve already mentioned a missing test pilot on the show, presumed to be a nod to Green Lantern, but it could turn out to be a way to introduce Savitar instead.