At the end of The Flash’s Season 6 premiere, The Monitor told Barry Allen that he “must die.”
There are good and bad reasons as to why I’m still on the fence about it, but let’s start with the good.
And so, the Scarlet Speedster spent the remaining episodes ahead of “Crisis on Infinite Earths” preparing Iris and his teammates for his demise.
When it came time to sacrifice himself, though, it was Earth-90’s Flash — because The Monitor didn’t say which Flash had to die — who took Barry’s place and disintegrated.