Icy is a young witch described as having a "Heart of Ice" (cuore di ghiaccio). As the eldest and most powerful witch of the threesome, she is the ruthless leader of The Trix and wishes to rule the universe. Lisa Ortiz voices Icy in the 4kids version. She first appeared in the Season 1 episode "Benvenuti a Magix!" ("Welcome to Magix!")/"More than High School" ("Welcome to Magix!").
Icy, like her name, is very cold and is often cruel for the sake of being cruel, ridiculing people she does not approve of. As she was taught by Headmistress Giffin, she and the other witches, Darcy and Stromy, hate Alfes fairies to a fault, and especially the WinxClub, specifically Bloom, Bloom because she evades them time after time. Before the Pixies were introduced in Season 2, she often called the fairies "pixies", as there was no other character called such at this time. After Season 2, she called them "twerps," "geeks," and "losers." She is often the most cunning of her sisters, and Baltor's favorite more often than Darcy or Stormy. An old nickname, mentioned in Season 3 by Darcy while hanging out in Baltor's lair eating ice cream, was "Six-Scoop Icy", because she ate so much ice cream when she was younger. It is unknown if Icy, Darcy and Stormy are actually sisters; "sister" is a term often used about good friends, or more likely, in a coven.