Caterina "Cat" Valentine (Ariana Grande) is one of Tori's strangest friends from Hollywood Arts. She is fun and energetic and sometimes oblivious. As seen in some episodes, she is revealed to be somewhat smart, just a little air headed. In a video on TheSlap she reveals that her full name is Caterina but only her grandmother calls her by her full name. It was also revealed by Robbie in "The Blonde Squad" when he yelled "Caterina Valentine, I will not sit here anymore and listen to you talk bad about yourself! You're adorable!" She is relatively friendly and liked by all of the students. She is sweet, naive, bubbly and happy, often unsuspecting of what is really going on around her. She has a playful nature, and has a very short attention span so she can easily be distracted with colorful items by the others when they want her out of the way. She can be somewhat of a drama queen, and doesn't take criticism very well. She often screams "What's that supposed to mean!?" when offended, which is very often and has become her catchphrase. Cat often says random and strange things which leaves the others, especially Jade, confused or annoyed.
Cat is also an extremely talented singer and actress, as seen in "Freak The Freak Out" where she sings a duet with Jade, and in the crossover episode "iParty with Victorious" where she shows a high vocal range. A running gag of the series is Cat often telling her friends or strangers about her brother, who seems to have many unnatural problems, all of which Cat doesn't seem to find strange or abnormal. She has bright red hair, that she dyed to resemble her favorite snack, a red velvet cupcake. Andre has a nickname for her "Little Red", which she took offense to at first, but then called it "creative". It is revealed in the "The Breakfast Bunch" that she is a vegan. Through the series, she has become more ditzy and over the top, with a higher-pitched voice and her abnormal conversations. In 2011 she crossed over to iCarly in the episode, iParty with Victorious.
In January 2013, Cat's parents move away to be with her mentally ill brother so Cat goes to live with her grandmother, who she calls 'Nona'. When Victorious airs its final season, Cat becomes a co-lead character on the crossover spin-off, Sam & Cat a sitcom that began airing in 2013. Sam & Cat become roommates when Cat's Nona goes to live in Elderly Acres. Technically, Sam & Cat met each other in 2011 in the iCarly episode, iParty with Victorious but neither of them made much contact. Sam and Cat later set up a babysitting service to raise some extra cash. Sam & Cat's home is stated to be 'the poshest apartment in the building'.