Jay Leno

JLVWNNOOOO the Rattata, affectionately referred to as Jay Leno by the viewers, was the second Pokémon that Red caught with a Pokéball (the first being Bird Jesus). Jay Leno was loved by many even though he didn't offer much in terms of fighting potential due to the overleveling of Bird Jesus and Abby leaving him unable to hold his own much of the time.

History
Jay was captured during the early part of Generation 1, shortly after the end of the Lost Days. As such, he was the first Pokémon to have a recording of the capture in TPP.

Jay Leno was the first Pokemon released during Generation 1, and also the first Pokemon released by Twitch Plays Pokemon. His release, like the release of Abby, which followed shortly after, was an accident (see: Release of Abby and Jay Leno).

During the chaos following the Releases, much of the community thought that it would have been better if the Rattata released had been Digrat instead of Jay Leno.

Name
Jay's name comes from the association of his LVNNOOO to late night talkshow host Jay Leno's last name.

Lore
Jay Leno never had much direct lore, due to the fact that he was released before much of the lore began developing. However, he and Abby, whom he was released shortly before, are often portrayed as being close friends or comrades.

Artwork from Gen 1 often depict JLVWNNOOOO with Jay Leno's signature chin.

Trivia

 * The same night JLVWNNOOOO was released, The Tonight Show had its first episode with its new host, Jimmy Fallon
 * Jay Leno was the first released released Pokémon of TPP.
 * Even though in fan lore Jay Leno is male if you bring him to gen 2 using old saves it is revealed Jay Leno is female.