Bess and Courtney Grumper, also known as the Grumper sisters are the scandalous sisters and the writers of the gossip section of Sheffield Institute's paper. They are voiced by Tracy Martin (Bess Grumper) and Courtney Peldon (Courtney Grumper).
The Grumper sisters love spreading gossip. They are the writers of the gossip section of the Sheffield Institute newspaper. They love to ridicule (especially when it comes to gossiping about others) anyone and get them in trouble at school to see their reactions, but the W.I.T.C.H. girls - and especially Irma and Cornelia - are their favorite targets.
Bess and Courtney are big into fashions and rivals of Cornelia. They have been known to diss Cornelia and her fashion sense, such as when they were walking through an alley and dissing Cornelia.
They are considered to be Principal Knickerbocker's pets, though they don't mind bribing students to stand behind them. They are considered rude by everyone except themselves due to their gossipy nature and are disliked by many students and especially by Irma because of the nasty rumors they make up about people, but seem to be more or less popular among boys (Uriah's Gang).
Bess Grumper and Courtney Grumper were born on May 22nd, 1991.
They almost got the W.I.T.C.H. gang to break up by telling lies, but in the end, they got what they deserved. Cornelia told them there was a "Costume Party" after the Christmas play, but no one else was in costume and the two conniving sisters were, much to their embarrassment and everyone's surprise and tremendous laughter, hilariously sitting around in pink-and-purple, puffy, ballroom gowns.
When they were walking through an alley, they dissed Cornelia and her fashion sense. Unbeknownst to them, Cornelia was also in the alley, so she threw a couple mud balls at them which scared them into running away.
They joined the school newspaper to write about fashion.
They started to work in the school's radio station, K-Ship. After running out of gossip, they decided to "create some". They made Martin sing a "lovey-dovey" song for Irma. Enraged, Irma lashed out at Martin and called him a loser, realizing too late that they were on air (as planned by the Grumpers and Uriah).