Hatsune Miku
Hatsune Miku was the first Vocaloid developed by Crypton Future Media after they handled the release of the Yamaha vocal Meiko and Kaito. The name of "Hatsune Miku" was conceived soon after the Vocaloid 2 announcements, when an English and Japanese vocal were developed for the character. The intended design was delayed and later used for Megurine Luka instead. Miku was intended to be the first of a series of Vocaloids called the ""Character Vocal Series"", which included Kagamine Rin/Len and Megurine Luka. Each had a particular concept and vocal direction.
Utau
Though the software is very popular in Japan, its origins and cultural impact are owed to the already established popularity of the Vocaloid software. UTAU itself was first made famous when the creator of Kasane Teto released the character posing as a Vocaloid character as part of an April Fool's joke in 2008. The influence of the Vocaloid software also led to both programs commonly being used side by side. Often popular UTAU mascots like Kasane Teto appear in VOCALOID-based media such as "Maker Hikōshiki Hatsune Mix".