In a very grisly and shocking storyline which played out on Boxing Day evening, we learnt that Fatboy had died in horrific circumstances - getting crushed in a car after a case of mistaken identity.
And murderous Ronnie Mitchell (Samantha Womack) was to blame after ordering thugs to kill her former flame Vincent (Richard Blackwood). But after sloppy instructions, Fatboy was kidnapped and targeted instead. Big oops.
Fans were devastated when they realised veteran character Dot had lost her best friend in Albert Square.
One shocked fan wrote: "Dot is going to be heartbroken. Fatboy was like a son to her. I'm going to miss their relationship. #EastEnders."
Actor Ricky Norwood played the role of Fatboy for six years, but show bosses decided to write him out earlier this year.
As the soap news trended on Twitter, many fans seemed furious with the storyline...
One female soap fan wrote: "On the list of 848656 characters that deserved to die, fatboy was not one of them #EastEnders."
Another blasted: "Fat boy?! Dead?!! He deserves a proper send off if he's really dead. What kind of nonsense is that?!! Dot needs closure. #EastEnders #Fatboy."
Ricky responded to the hundreds of messages by tweeting: "Wow!!! Ohhh my goodness!!! Sending soo much love out there to you guys.! #Fatboy #EastEnders #RIPFatboy."
He added: "I will do a proper tribute to FATS 2moro.But had to say thank u2u guys.Your support is unconditional means more than I can fit in a tweet!"
He also paid tribute to his character, saying: "Bye fat's..!! It was so fun to play you..!!Gona miss u .!!Fat's was only supposed to be around for 3months managed 6years..!! # bbceastenders."
Here are some of the shocked responses from EastEnders fans, including Jacqueline Jossa who wrote: "Aww FATBOY is dead great ep tho!! Drama drama!!"
Not happy with Eastenders....can't believe fatboy is dead. What a horrible way to kill off his character. Not happy at all.— Audrey Burrell (@Audrina77) December 27, 2015
Dot is going to be heartbroken. Fatboy was like a son to her. I'm going to miss their relationship. #EastEnders— Sam (@sxmwillixms) December 26, 2015
on the list of 848656 characters that deserved to die, fatboy was not one of them #EastEnders— tanya-louise (@DELPHlNUS) December 26, 2015
Still can't believe they killed Fatboy. #EastEnders— DJ IRONIK (@DJIronik) December 26, 2015
Aww FATBOY is dead great ep tho!! Drama drama!!— Jacqueline Jossa (@jacquelineMjos) December 26, 2015
'Fatboy' is the No:1 UK trending hashtag right now! #EastEnders— BBC EastEnders (@bbceastenders) December 26, 2015
EastEnders continues on Monday 28 December 28 at 8pm on BBC1.