4. Jay Garrick
This won't be the last time you see a speedster played by John Wesley Shipp appear on this list. The veteran actor is best known for playing Barry Allen on the original The Flash series from CBS in the '90s, but he also played veteran speedster Jay Garrick on the CW reimagining. Jay was DC's original Flash, so it was rather fitting that Shipp played the character on the show. He's great in the role too.
Jay is always on hand to provide Barry with wisdom and knowledge - wisdom and knowledge that only comes from years of experience as a speedster. He's an accomplished superhero, who knows all too well about the dangers of messing with the timeline. Remember, he was the one who warned Barry against altering things during the third season. He also advised against throwing a nuclear bomb into the Speed Force as it could have destroyed it.
The character is a remarkable hero capable of the vast majority of feats that his younger Earth-1 counterpart could do. While he didn't develop some of the more advanced abilities that Barry did (like Flashtime), he did develop some of his own - like that awesome ability to absorb lightning that he showcased in the series finale. Furthermore, his knowledge as one of the earliest speedsters in the Arrowverse's multiverse has seen him - and Team Flash - through some major trials. Heck, he even figured out how to charge his helmet with lightning and throw it like a fast frisbee - now that's cool!
Jay may have slowed down for a period of time due to his age but he defied age more often than not, proving himself a valuable ally to Team Flash and one of the best live-action speedsters we had ever seen.