The band and the masks

Current members ("the family unit", as they describe it) of Slipknot include:

"0" Sid Wilson, turntables.
Mask: 8-9 different gas masks. He names them all.
Nickname: "Monkeyboy"

"1" Joey Jordison, drums.
Mask: An expressionless Japanese Kabuki mask, with scars painted across the forehead and mouth.
Nickname: "Superball"

"2" Paul Gray, bass.
Mask: Paul has two masks: The tight, normal one that tends to look like a beaver, and the loose, more pig-oriented one. He says it reflects his indulgent personality.
Nickname: ??

"3" Chris Fehn, custom percussions.
Mask: A pinocchio-type mask with a 7½ inch nose and a zipper for a mouth.
Nickname: "Mr. Picklenose"

"4" James Root, guitars.
Mask: When he joined the group, he was forced to wear a bondage hood, which was originally worn by the member he replaced, Josh. However when Slipknot played sweat would be trapped inside the mask so he made a Jester's mask to reflect on his Jester-like personality. It has a zipper for a mouth and a spike for a chin. He says that "it is smelly and disgusting, and everyone gets pissed at me because the mask stinks up the whole house."
Nickname: "Jim", "The Peach"

"5" Craig Jones, sampling.
Mask: A diver's helmet (found at a gas station), which has about 25 nails sticking out of it. The nails are real, and they are 6 inches long. His old mask had a tube hanging from the bottom, and the new one doesn't.
Nickname: "133 Mhz"

"6" Shawn Crahan, custom percussions.
Mask: A clown mask. He was the first one to wear a mask in the rehearsals.
Nickname: "Kong"

"7" Mick Thomson, guitars.
Mask: He has two masks: A green painted hockey mask and a metallic leather mask.
Nickname: "Log"

"8" Corey Taylor, vocals.
Mask: A crash test dummy head. The dreads are partially his own hair.
Nickname: "The Sickness" (though he prefers "Faith")

Ex-members:

Andreas Colsefini: The original lead vocalist, who was replaced by Corey Taylor during the recording of Mate. Feed. Kill. Repeat..
Josh: The original rhythm guitarist. Left for "No apparent reason" after the recording of the self-titled album. Plays on all tracks except for Purity. He was replaced by James Root.
Greg "Cuddles" Welts: The original custom percussionist. He left not long after he joined and was replaced by Chris Fehn.