The Flash mythology in the comics is a dense one full of costumed villains, time travel, super-intelligent gorillas, evil magicians, paradoxes, and The Speed Force. It is a lot of material to cover, but the Flash TV series has done a very admirable job of bringing them to life over the last five seasons.
We've got to see Gorilla City, glimpses of The Flash Museum, and Barry finally get his iconic costume ring.
Still, there is much more in the mythology for the show to tap into. Some elements are so iconic that if the series were to end without them ever being realized it would feel forever incomplete.
5. The Flash (Vol 2) # 134 "A Day In The Life Of The Flash"
The Flash's second year was a season-long build up to Jay Garrick A.K.A. The Golden-Age Flash although we didn't know it at the time. A shocking twist revealed that original TV Flash actor John Wesley Shipp was playing the real Jay. It was a great entrance for a classic character, but little has been done with him since.
The series Jay Garrick is presented more as a "Speed Angel" than as a man. He appears when needed and guides Barry, but has no background of his own. What is his secret origin? Is he part of the Justice Society of America? Family? We know nothing about him. Flash #134 could be the perfect answer to all of these questions while helping the series current struggle of not having star Grant Gustin available for all the episodes.
"A Day in The Life of The Flash" is a wonderful story about a hero, but mostly about life. Work, marriage, getting older, friends, and living for today. Jay saves the day from random fantastic threats like a Reverse Golden-Age Flash robot all while trying to help a terminal friend. He also fits in career day at an elementary school, lunch with Wally West & Dick Grayson (great moment with Wally & Jay racing to see who can pay the check first), and celebrates his anniversary.
This was a fun yet poignant standalone story that would be a perfect episode to do in Grant Gustin's absence. It would offer the rarely explored perspective of a senior super-hero.