With Zoom now in the fray of The Flash, and is identity still being a mystery, I have an idea on who he MIGHT be, so don't quote me on anything.
My choice is Earth-2 Henry Allen, mainly because of that the same people on Earth-2 do completely different things than on Earth-1, and because of this:
Now, if you look closely, it looks that the actor in Zoom's suit and Henry Allen have the same eye color, and also, it looks they have the same jaw line, but still hard to tell with Zoom's full suit on.
And John is a big bigger than Grant, and just by looking at Zoom, he looks to be slightly bigger than Barry, but that also could just be the costume.
Tell me who you think Zoom is in the comments below!