Currently there r many theories circulating around about who is Zoom. Some say Henry Allen earth 2 and others say jay either earth 1 or earth 2.
There was another theory that it was Joe West earth 2 but that died with the 'Welcome to earth 2' episode on flash.
However I am writing to suggest why it is actually Joe. Many people think Joe died because the heart monitor showed zero. However in season 1 of the flash when Barry was first struck although he was alive it was thought that he was dead since the heart monitor showed zero. However we were told this was the case was his heart was beating too fast for the monitor to register and I think Joe slowed and sped up his heart rate.
Now some people may be thinking but what about the metahuman detectors. How would he have kept himself hidden but I would say it was simple as we saw how easily iris dismissed it when it was beeping because of Barry so I think it may be a regular thing for the detectors to be on the fritz. However that is just an assumption.
Now many of u may still think but you have not shown evidence of it not being jay or Henry.
Why not jay?
I would start of with why it is not jay. The writers of arrow and flash like pointing us to one person and this time it's jay. Many would think jay because of the hunter zoloman name drop ( which is the name of the real zoom in the comics) or because he lied to team flash, or because he said he was obsessed with getting faster or lastly because it would heal him but I think he is just a trogan horse that is meant to make people think it is him kinda like Eddie thawne in last season.
Finally why it is not Henry. In the earth 2 visitation episode you note how iris says your mum called and not your parents although on the phone it says mum and dad which leads me to believe they r either separated or Henry is dead either by natural causes or similar to how Barry's mum died. Although there is a dad icon there I assume since Barry and iris share their home it is for her dad.
Other possible candidates are Eddie, Barry's mother or someone yet to be met. But I doubt it would be any of those as we would need a few episodes to flesh out the character.
Comment on what you think. N if ur not too busy subscribe to my youtube channel where I plan to start doing a lot more superhero topics reviews and theories.