1. Ralph Dibny One of my favorite relationships in the comics is Barry Allen and Ralph Dibny's. He operates in Central City and is one of The Flash's best allies. He was even one of Barry's Groomsmen. I know they already referenced Ralph Dibny as one of the people who disappeared after being hit by the particle accelerator, so he must be out there somewhere. One of my favorite parts of Ralph isn't his stretching powers but his detective skills. I would almost rather see them introduce him as a detective, either as a PI or as a detective that get transferred to Barry's department in central city, discovers he is the Flash through deduction and detective work, and then gets his stretchy powers and becomes a hero. I'd like to see a Ralph established where he's already married to Sue. The Ralph/Sue relationship is also a great dynamic in the comics. 2. Hal Jordan Obviously Hal/Barry Brave and The Bold is one of the best hero/hero relationships in DC. Green Lantern is obviously a hugely popular and well known character so he'd be a great get for the CWverse. Also Hal and Oliver being best friends as well could make it so the CW's Trinity would consist of Lantern, Flash, and Arrow which are probably my 3 favorite characters in the entire DCU anyways. 3. Jay Garrick Almost didn't include because it seems like he's coming next season for sure already, but I have always loved Jay Garrick and his relationship with Barry. Barry growing up a giant fan of Jay Garrick's flash comics, and even playing Flash as a kid is one of my favorite parts of The Flash, and although that will have to be dropped in the CWverse the fact that their introducing Jay Garrick is amazing. I would also love to see Barry go to Earth-2 where Jay Garrick is an older, possibly already retired Flash who has already established the Justice Society (Also, since the Superman from The Supergirl pilot is already older and established, I was thinking the Superman in the Justice society could be the Superman from Supergirl, and this could be a cool way to tie Supergirl to the CWverse.) 4. Wally West! Another obvious one! I don't know if Wally's original origin of being Barry's nephew who is randomly struck by the same lightning as him would work on the CW Flash. Wally could be a Flash from another timeline like Jay Garrick, but I also thought of another possible origin: In the comics, Iris's real parents are from the future. I was thinking there could be a storyline involving revealing that Iris's mother and Joe's ex wife is actually from the future sent back in time to ensure that Iris is born in Barry's timeline to be his lightning rod (something people in the future know The Flash needs to have) You could have Wally be Iris's nephew on her mother's side who is also from the future (similar to BART Allen's back story) and travels back because he is born with accelerated aging and speed effects that Barry needs to fix. 5. Booster Gold With Rip Hunter being a big character in LOT and time travel being such a big part of The Flash, I'm kind of surprised Booster Gold hasn't already been talked about being introduced. I think you could very naturally fit Booster Gold into The Flash, especially the older Booster Gold who works with the time masters and trained his son to be Rip Hunter.