Shang Tsung is dead. Liu Kang's bio says so.
Sub-Zero The Older Brother is dead.
Sheeva is dead.
Frost is dead. (Someone who read Sub-Zero's entire bio at GameStars confirmed it).
Can't think of others right now.

Isnt' Kano dead too???
Liu Kang is dead.
Shang Tsung is dead.
Kitana supposedly died but was resurrected. (Not konfirmed).

Kano was killed by Mavado in Mavado's ending. (Deadly Alliance) That is why Kabal is now leader of the Black Dragon.

Oh yeah, Goro is dead.

Kitana is not dead as far as I've heard, Bo Rai Cho is supposed to be the general of the Edenian army I believe, appointed that status by Kitana, so if she really is dead it probably happens sometime mid-point in Deception like in a battle or something, so bottomline: if she is we'll find out in Deception. If not then she's alive.
Shang Tsung, Raiden, and Quan Chi are a mystery for now, Raiden sacrificed himself to attempt to kill the Dragon King with Shang and Quan chi right next to him, BUT they never did say if those two died, obviously though Raiden is in but it is still unclear if he's a undead like Kang, or he was ressurected like many others apparently have been in the past.
Shao Kahn is obviously dead, or is he?
Kano is dead, thus Kabal becomes the new leader.
Mavado may be dead or not, this is one of my theories here, because with the end of the Deadly Alliance, The Red Dragon aren't exactly safe now are they?

Shinnok is dead
SCorpion has always been dead...

Motaro is dead by Sheeva
Sheeva is dead by Shao Kahn
Kintaro is supposed dead by Raiden
Hsu Hao is dead by Jax

Kabal killed Mavado.

Dead? As "forever"???........No one, but so far:
Kitana (Killed by the DA and Ressurrected by the DK)
Johnny Cage (Killed by an X-squad, revived later, but according to Vogel, Cage never died)
Kano (Revived with Magic thanks to Motaro when Sonya won the battle, according to Kira's bio, he has been killed by Mavado)
Motaro (Killed by Sheeva)
Sheeva (Betrayed by Kano, Killed by Shao Kahn)
Frost (Killed herself when stealing the Dragon Medallion according to Sub-Zeros bio)
Shang Tsung (Killed by Raydens blast)
Mileena (Killed by Kitana, revived by Shinnok and Kahn)
Liu Kang (Killed by the DA)
Scorpion (Killed by Original Sub-Zero, killed by Quan Chi in MKDA)
Sub-Zero (Original elder brother, killed by Scorpion)
Goro (Killed by Noob Saibot)
And so many many more.

Kabal hasn't killed mavado, just cause he has his hookswords doesn't mean that he did, he could've made or found or bought new ones. Please don't post things that aren't true unless you have proof dude, it confuses the newbs, we don't want threads saying "OMG Kabal killed Mavado?! that suxxorz!1". Just wait until Deception comes out, we'll find out for sure on whats what then.

I don't think Quan Chi or Shang Tsung are acually dead. I think at least one of them is waiting in the shadows until next game.