On Thursday night (October 17), the Walford market trader was seen 'turning to the dark side' and brutally attacking a man, leaving him in a bloodied mess on the ground.
It's not the first time Martin has lashed out in anger with his fists, but something about the way he looked made viewers fear he'd lost control.
And they believe the storyline is all too similar to Coronation Street's Gary Windass plot, in which the builder turned bad after a series of unfortunate incidents.
Viewers saw Martin in yet another scuffle as a result of Ben Mitchell's merciless campaign to blackmail him.
When Ian asked Martin for his takings from Monday, he was far from impressed by the amount and questioned why he'd had such a slow day.
Not in the mood for Ian's moaning, Martin lashed out and grabbed him by the collar, warning him to back off.
So is Martin Fowler going to turn into Gary Windass?
Witness Ben jumped at the chance to twist the knife in, and told Martin he was only short on his takings because he paid off an elderly lady's debts.
Ben taunted him with the words "kindness is a weakness" before warning Martin that he needed to toughen up...
Ordering Ben on a new debt collection job with Tubbs, Martin was distressed as the 'job' caused him to miss Bex's mental health appointment.
In dark scenes, the pick-up went horribly wrong when Martin was tricked and two heavies armed with steel bars came to threaten him...
The situation spiralled out of control as Martin violently attacked the two men, repeatedly punching one of them on the ground.
As Martin walked away with a glint of determined malice in his eye, fans now fear he's on the verge of becoming the hardened debt collector Ben wants him to be.
But some viewers believe this is reminiscent of Gary Windass' character development in Coronation Street.
Writing on Twitter, one fan said: "EastEnders using the same storyline about money lenders as Corrie? Will Martin take over like Gary Windass? Time will tell."
Another typed: "So is Martin going to turn into Gary Windass? #EastEnders #Corrie."
A third said: "This storyline of Martin being forced to be a debt collector and struggling with his conscience... Haven't we just had that with Gary in #Corrie #EastEnders."
"Looks like Martin has been hanging out with Gary from #Corrie #EastEnders," joked one.
Another said: "Well Gary Windass was made into a thug bailiff on Coronation Street, so guess what? They have made Martin Fowler into the same on EastEnders. I think they are all running out of storylines, so are pinching each other's."
Soap boss Kate Oates recently hinted that Martin could be Albert Square's new villain...
She told The Sun: "We will see a very different side to Martin, which James [Bye] is loving, I believe.
"It gives him a chance to get his teeth into something different."
Some viewers even believe Martin will KILL his nemesis Ben.
Do you think Martin's storyline is similar to Gary's? Leave us a comment on our Facebook page @EntertainmentDailyFix and let us know what you think!