I believe Terry has cleared this up on Word player.
The four people are indeed, Will, Tia, Elizabeth and Barbossa.
Will has tried to kill Jack twice. The first time is in COTBP. He hits Jack in the head with an oar, and leaves him at the mercy of the pirates who want to kill him. The second time is on the Isle Cruces during the three way sword fight. He flat out threatens Jack's life.
In the script for the third movie, it's insinuated that Tia tried to kill him.
Ha, I'm just telling you what Terry, one of the writers of the film firmly stated and since he co-wrote the series, I'd take his word for it.
I can try and find the quote in which Tia is implied in trying to kill Jack but even in DMC, he is frightened of her. When he goes to visit her, Gibbs is worried that she might try to "stab him in the back". To which Jack replies: "It's me front I'm worried about".
And in AWE: This is the scene which we're currently discussing:
JACK
Why should I sail with any of you? Four of you have tried to kill me in the past.
(he gets to Elizabeth)
One of you succeeded.
Will is startled. Jack notices.
JACK (cont'd)
She hasn't told you? Then you'll have lots to talk about while you're here.
(to Tia Dalma)
As for you --
TIA DALMA
Oh, don't tell me you didn't enjoy it at the time.
JACK
That's fair. All right, you're in.
Will has tried to kill Jack twice and will make another attempt in AWE. Don't let the facade fool you.
I thought it was obvious ...
Posted by Terry on Thursday, 29 March 2007, at 1:01 a.m., in response to Due to rampant speculation, I hope a T does answer@, posted by Sparrabeth Rules on Wednesday, 28 March 2007, at 8:01 p.m.
... it has to be Barbossa, Will, Elizabeth, and Tia Dalma.
The members of the crew Jack lets off the hook (Cotton, Marty, Pintel, Ragetti, Cotton's Parrot) because he sees Barbossa as the architect of the mutiny.
http://www.wordplayer.com/forums/movies/index.cgi?read=96163
Plus, when Jack asks why Will makes all those swords and practices with them he says it's so he can kill a pirate when he finds one. Also, he tries to kill him on Isla de Cruces and he's about to let Norrington do it instead until Jack opens his mouth and causes trouble again. I think Jack considers both those times attempted murder.
I want to know how he got out of Tia trying to do him in. I think of all the 4 that tried, she would succeed the easiest.