Franchise: PaRappa the Rapper

PaRappa the Rapper co-creator Rodney Greenblat has said in response to a fan email that, if he were to do a new Um Jammer Lammy game, he would have Lammy and Katy Kat as a romantic couple. A few years after this, he would begin posting annual Valentines' Day images to his Twitter accounts with Lammy and Katy together.

Notably, one of the interviews in Um Jammer Lammy Now! has Katy laugh off a question about if she has a boyfriend.

PaRappa the Party Mix is a music album that was released in Japan to promote PaRappa the Rapper 2, containing a mix of PaRappa 2 music and mainstream rap songs. Despite being a tie-in for a family-friendly video game series, many of the songs contain adult elements common with mainstream hip-hop, such as violent, sexual, misogynistic, and vulgar lyrics, as well as uses of the colloquial ethnic slur "nigga".

The PaRappa the Rapper anime had a highly troubled production. The series was aimed at a younger audience than the games' developers wanted due to teenagers not buying toys and the characters were aged down as a result, series character designer Rodney Greenblatt was given very little input on the series' stories or art, despite having to make new character designs every week (noting that characters often appeared off-model), and the series failed to garner an audience due to being aired at an awkward time slot where it would often be delayed for baseball games. Greenblatt speculated that the drama over the anime's production led to the PaRappa franchise being put on its currently-ongoing hiatus.

It has been claimed in interviews that the name "PaRappa" is a pun on "parappa", a supposed Japanese word meaning "flat" or "paper-thin", and the English word "rapper". This appears to be a slight mistranslation, as the word "parappa" does not exist within Japanese, but the word "パラパラ" (para para) seems to be a more likely origin, a Japanese term for flipping through a book, which would have flat pages. The term is also used for a Japanese form of disco dancing, which could also be seen as part of a pun, given that the series takes influence from a lot of different genres as opposed to just rap, with PaRappa the Rapper 2 having a noticeable disco influence.

Despite retaining "the Rapper" in its title and its source material being a music game, PaRappa only ever raps once in the anime adaptation of the PaRappa the Rapper franchise - that being the penultimate scene of the final episode, with the song sung being a rendition of PaRappa the Rapper 2's final stage, Always Love.

Masaya Matsuura came up with the idea to allow CD-generated levels in Vib-Ribbon after receiving letters from PaRappa the Rapper fans asking for spin-offs based on their favorite musical genres.

Sunny Funny, Katy Kat, and PJ Berri already existed in Rodney Greenblat's art before PaRappa the Rapper entered development.

Before he was made a dog, earlier ideas for PaRappa the Rapper's species included a shrimp, clam, onion, reptilian kaiju, bee, and fox.

PaRappa the Rapper co-creator Rodney Greenblatt had a bittersweet response to PlayStation All-Stars Battle Royale, appreciating that PaRappa was in a new title and finding the game fun, but disliking the presence of PaRappa in a battle game with lots of realistic weaponry.

One of the background characters in the "Fire Fire!" stage of Um Jammer Lammy, a blonde-haired and beige-furred firefighter dog with a crop top, is shown in various PaRappa the Rapper spin-off media as being PaRappa's mother.

Dred Foxx, who voices Parappa, rapped the lyrics for "Unknown from M.E." (Knuckles' Theme) in Sonic Adventure.