The following information was taken from the The Chanels page on the Scream Queens Wiki.

The Chanels are a popular group of people that participate in the sorority, Kappa Kappa Tau. They are all best friends and are known for being cruel to other people of the university.The leader, Chanel Oberlin, calls them that because she doesn't know their names and doesn't care about knowing their names.

Chanel Oberlin

Chanel Oberlin, but is also called Chanel #1 is a main character on Scream Queens. She is the co-president of the Kappa Kappa Tau sorority along with Zayday Williams and the leader of her own clique The Chanels, a group named after her.

Chanel is really ruthless, and fashionable. All her life, all she wanted to do is to have a great boyfriend, be the president of Kappa Kappa Tau, and rule the roost. When this finally happened, she became the most popular and the meanest girl of Wallace University.

Chanel #2

Sonya Herfmann, also known as Chanel #2, is a recurring character on Scream Queens. She is introduced in Pilot as one of Chanel Oberlin's minions and part of the Kappa Kappa Tau sorority. She is murdered by the Red Devil in the same episode.

Chanel #2 has a cute personality, and she is loyal to her fellow Chanels. She is kind of shy, but not afraid to tell what she thinks.

Chanel #3

Sadie Swenson, better known as Chanel #3 is a main character on Scream Queens. She's one of Chanel Oberlin's minions and a member of Kappa Kappa Tau.

Chanel #3 is a sassy low key individual, she is very quiet and popular and she doesn't know if she likes Chanel.

Chanel #4

Chanel #4 was part of the Kappa Kappa Tau sorority and Chanel Oberlin's clique The Chanels, until her death that is mentioned in Pilot.

It is mentioned by Chanel Oberlin that Chanel #4 got meningitis and, despite Chanel #1's objections, left to go home, where she eventually died. 

Chanel #5

Libby Putney, better known as Chanel #5, is a main character on Scream Queens. She's one of Chanel Oberlin's minions and a member of Kappa Kappa Tau sorority.

Chanel #5 is very uptight and educated, and is always competitive to be Chanel's favorite.  She is very protective over Chanel and will do anything to please her because Chanel gives her popularity in exchange.

Chanel #6

Hester Ulrich, also known as Chanel #6, is a main character on Scream Queens. She is a pledge for the Kappa Kappa Tau sorority who suffers from scoliosis. After a makeover given by Chanel Oberlin, she became a member of The Chanels.  

Hester is crazy, two-faced and obsessed with death. She is incredibly really different from the other girls in Kappa. She has a serious obsession with death and dead bodies and strangely gets sexually attracted to them and always loves the idea of death flowing into her mind and into Kappa Kappa Tau. She is a massive wannabe Chanel and will do anything to please and protect Chanel and be a huge loyal minion towards her, but at the same time, she wants to take everything from Chanel and become the true leader of Kappa house and wants to actually become Chanel #1 and will do anything to steal Chanel's boyfriend Chad.