Hatsune Miku was the first release for the Vocaloid 2 software, and is arguably the most popular of the Vocaloids to date.  She is known for her extremely high octave range and ability to sing a multitude of genres.  Her outfit is modeled after a 16-year old's Japanese school uniform, however the inputs and readouts incorporated show that she is synthetic.  Known for her massive twin pigtails, she also tends to carry around a very large leek or two.  Miku's vocal library is currently undergoing alterations to make her sound more human than before.

Miku's popularity started when a user on Japanese video-sharing site NicoNicoDouga posted a video of her covering the chorus of Ievan Polkka, a Swedish song that is mainly gibberish.  From there, her popularity spread like wildfire, and NicoNicoDouga became the premiere place for users to post their produced songs.  Most early work became canon, so much so it is nearly impossible to mention.  Recently, on her second birthday, an animated video came out encompassing her history until that date.

Riding Miku's wave of popularity was Vocaloid production group Supercell.  They initially issued many different songs that made up Vocaloid canon.  Most recently, they were commissioned to create the end theme to Bakemonogatari, an Anime released to Japan in the Fall season of 2009.

One of Supercell's most famous videos, Black Rock Shooter has expanded so exponentially that it, and its encompassing canon have been animated into a new series that will be broadcast in Japan in the Spring of 2010.  This will be the first ever Vocaloid production that has been turned into a professionally-animated product.

Miku has been featured in many places outside of the television and online.  SEGA has released a game for the Sony PSP called Project DIVA that features her, and has announced a sequel project to arrive in Japanese Arcades this spring.  Miku has appeared in the virtual Playstation Online world, with her own section heavily featured, and she has even given 'live' concerts in front of thousands of avid fans.