|Appearance||White female human with black hair and brown eyes.|
|Debut||The Secret Life of Pets|
|Voiced by||Ellie Kemper|
Katie is very open-minded and very sweet; she doesn't mind a little mess of her apartment. She always tries to make sure her dogs are happy.
Katie has very short black hair that is always gelled down with a pink clip. When home, she is commonly seen wearing a long-sleeved striped shirt with red pants and brown boots, alongside a blue puffer jacket. She always seems to be wearing her pink, blue, and green long scarf. At night, she wears a white short-sleeved shirt, wears pink striped pajama pants, and blue slippers with white spots.
Katie first adopted Max, by the time he was just a puppy, after she found him abandoned in a cardboard box, and then they move into her apartment in the Apartment Building. After that, they both spent many moments together for years; like going to the park, spending time in the rain, helping clean the dishes, and admiring the skyline of New York while eating pizza.
Katie needs to go to work almost every day, but Max can't understand where she is going, which beings him lots of disturbance. Though many nearby pets visit her apartment pretty often, she doesn't seem to notice or feel annoying about it. One day, Katie brings home a stray dog Duke, and she is excited that Max already has a brother, but he isn't. Despite Max's complaints, she doesn't seem to understand his disturbance - because what she hears from Max is barking instead of talking.
The next day, Katie leaves again for work, now leaving both Max and Duke alone; after coming back home (without having noticing that her dogs embraced an adventure), she is glad to see her pets getting along well; even though many things in her apartment are in a mess, she doesn't feel angry. In the end, she and her two dogs watch the skyline of New York outside the apartment.
- Katie has a violin in her apartment and also a somekind of musical trophy is seen on her table, which can mean that she has won a musical competition with her violin.
- In the scene, where Katie is brushing her teeth, you can see from her shirt that she goes or has went to Dartmouth College in New Hampshire, which actually is a real college.
- "Sit...Spin...Speak! "
—Katie playing with Max before she leaves for work
|Buddy • Chloe • Duke • Gidget • Max • Mel • Norman • Pops • Sweet Pea • Tiberius|
|The Flushed Pets|
|Derick • Dragon • Nitro • Ozone • Password Snakes • Ricky † • Ripper • Snowball • Tattoo • The Alley Cats • The Sea-Monkeys • Viper †|
|Dummy • Gino • Guillermo's Iguana • Leonard • Marilyn's Cat • Myron • Peanut • Pepe • Reginald • Runty • Shelly • The Boston Terrier • The Collie • The Golden Retriever • The Papillon|
|Fernando • Maria • The Piranha • The Sausages (Frank • Timmy) • The Squirrels • The Pigeons • Unnamed Chihuahua|
|Animal Control (Fourrage • Menard) • Buddy's Owners • Chloe's Owner • Fred † • Harold • Gidget's Owners • Gino's Owners • Guillermo • Guillermo's Girlfriend • Katie • Katie's Grandma • Leonard's Owner • Marilyn • Mel's Owner • Molly • Norman's Owner • Pepe's Owner • Reginald's Owners • Steve Cabin • Sweet Pea's Owner • Tiberius' Owner|