9. The Flash (Season 5)
Barry Allen's Scarlet Speedster possessed some of the absolute greatest costumes in the history of superhero television during the first four seasons of the show, but the change that came along in Season 5 was unquestionably to its detriment.
Dropping the now-iconic leather jacket and pants, Grant Gustin instead donned a new all-in-one bodysuit that clung very tightly to his physique. While the young hero undoubtedly pulled the look off, the suit's bland design just lacked any character whatsoever and it was so neat that the oversized cowl looked like a helmet. And don't even get us started on the missing chinstrap.
It certainly wasn't as bad as many made it out to be and when worn without the mask it was actually pretty good, but when Stephen Amell donned it in the Elseworlds crossover it just looked like well-designed cosplay.
Thankfully, it didn't last long as extra padding, more golden accents and a completely different cowl provided Gustin with a far superior look in Season 6.