Jack, played by Scott Maslen, is currently riding high with 43.5% of votes in a Digital Spy poll which invites readers to solve the mystery.
Show bosses yesterday (June 6) announced that Kat will succumb to temptation by cheating on husband Alfie once again this summer, sparking a long-running storyline. However, viewers will be left in the dark over who her secret boyfriend is for quite some time.
Jack, Derek, Max, Michael and Ray have been announced as the five main possibilities. However, womaniser Jack currently has more than double the votes of any other suspect in Digital Spy's poll.
Queen Vic chef Ray is currently seen as the second most likely man with 20.1% of the votes, while bad boy Derek and twisted Michael have taken third and fourth place respectively.
Despite his history of affairs, Max is seen as the least likely option with just 8.8%.
EastEnders fans will see the storyline begin on screen later this month and run until the autumn.
> Cast your votes in our poll here
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