James Patterson's Witch & Wizard series, in the back of each book, features descriptions of books, celebrities, etc. banned by the characters' government, which are all parodies of real-life books and people. There is one parodying Warriors:
THE BRAWLERS: The story of a pack of sentient dogs - some stray, some pets - seeking to fulfull a 'prophecy'.
In the graphic novel of Coraline, there's one panel toward the start where it says "She'd already read all her books", and it shows a stack of books. One is the cover of the first Warriors book, Into the Wild.
In the Pretty Little Liars episode "Run, Ali, Run", Aria remarks; "A's been stalking you for two years like a warrior cat..."