Katherine "Katie" Fitch is a fictional character in the television series Skins, played by Megan "Meg" Prescott. She is introduced in the third series. Her twin sister Emily is played by Megan's real-life twin Kathryn "Kat" Prescott.

Katie—along with identical twin Emily—was born in 1992 to Jenna Fitch, a beautician turned wedding planner and Rob Fitch, the gym owner of "Fitch Fitness". Being the older twin by a few minutes Katie is notably more aggressive, controlling, and extroverted in contrast to younger twin Emily's quieter nature. During their childhood she and Emily created a secret language that only they can understand called "Twin". In the first episode of series three Katie states with pride that she has never been without a boyfriend since age seven. On her official Skins page, she discusses the difference between her and her sister.

I have an identical twin called Emily. We have learnt that even though we look the same, we are different and in order for people to be able to recognise this, we must be real, we must be ourselves, not each other. As for the future, fuck ambitions, they just restrict you. I do what I want, when I want and don't think about anything long term. Who knows what tomorrow could bring?

Considered by many to be shallow, self-centred, and somewhat ruthless—especially towards Naomi Campbell, Effy Stonem, and her sister Emily, Katie is mainly on a quest for popularity during series three. Though she eventually forms a relationship with Freddie McClair, the couple is short lived after she suspects his feelings for Effy, where an argument that leads to an accident between her and Effy nearly threatens her life. This event would prove to be a life altering experience for Katie, whose sensitive, highly insecure nature, and fear of being alone is revealed.

By the fourth series Katie's personality develops significantly. She decides to get a responsible boyfriend and direct her energy into her mother's wedding planning business "Let's Get Fitched", though upon learning that she is infertile, she begins to question the future she had always imagined for herself as well as her own identity. However, after coming to an understanding with her parents and reconciling with Emily (while tolerating Naomi), and gaining friendships with Thomas, Pandora, Effy and Freddie, Katie becomes fully integrated into the gang and more openly expresses a caring side.

Katie has also kept her outspoken personality, most vocally standing up for Kanye West in the aftermath of the 2009 MTV Video Music Awards.

Unlike most of the other characters, Katie is shown to be selective regarding drug use; although she spikes the brownies at Pandora's birthday party, she desires to keep the gang's party in the woods free of drugs, and does not smoke until Effy teaches her in series 4.

In the opening episode "Everyone", her hostile behaviour towards Emily is made clear as she tries to shed her twin, establishing her individuality, and seemingly trampling on her sister as she does so. She does it to the point where Effy comments that Katie treats Emily like a "doormat". She wants to be popular and tries to befriend Effy Stonem, who seems to be the most popular girl in school. Katie is deeply homophobic against Naomi, as she thinks that Naomi forced herself on Emily.