So I saw Flash put out high quality photos of the "Enter Zoom" episode. Looking at Zoom's face for a minute I started thinking who it might be, first thing I noticed that only thing we have going here is the eye color. After that I started looking around the main cast, who has Dark Brown eyes to fit the role, unless of course it's somebody totally new. I looked at male cast only because we have heard Zoom talk and he does sound like a male, though it seems his voice is changed from a normal human voice all the time.
So first I of course checked Eddy Thawne, who had bluish eyes.
Then I looked at Wells, who also had Bluish eyes.
Next I thought it might be Barry, I looked at least 50 different Grant Gustin photos and it looks like his eyes are way too light Brown to match Zoom's eyes.
That lead me to the last person it could be, now take this Theory with a grain of salt, it's a massive stretch and also the eyes could be CGId to a different color or they might be wearing lenses. But my theory puts him Barry's dad, he is the only male main cast who has Dark Brown eyes which match Zoom's eyes. This could also be a interesting battle Barry fighting against his dad, raise the already massive drama in he show. So according to my Theory it might be Henry Allen.