7) Savitar
Savitar is pretty unknown to general audiences, so his inclusion could be an interesting leap into the deeper, darker reaches of the DC catalog. The powerful speedster got his powers much like Barry did, by being struck by lightning, though he was testing a supersonic fighter jet during the Cold War instead of hanging out in his lab/loft.
Savitar’s jet was struck by lightning once it hit top speed, and he crashed behind enemy lines. He miraculously survived and became obsessed with his newfound powers. He started going by the name Savitar because it means “God of Motion” in Hindu, and over time he perfected his abilities along with developing new ones, including the power to create a forcefield around himself, to give people and objects kinetic energy, and to heal his own wounds almost instantaneously.
Eventually, he gained followers and became the leader of a cult called the Thunderbolt Agents. He’s also fully tapped into the Speed Force, the outer-dimensional plane in which all speedsters draw their power. It has yet to be fully explored in The Flash, so Savitar’s arrival – and his mastery of the Speed Force – could be a great way to introduce its larger science-fiction elements into the show’s mythology.