Vocaloid (portmanteau of 'vocal' and 'android' stylized as VOCALOID) is a singing voice synthesizing software created by university researcher Kenmochi Hideki and the Yamaha Corporation.
Not pictured: The hundreds of other virtual singers that couldn't fit even if we tried.
note Clockwise from top-left: Kagamine Len, Gumi, Camui Gackpo, IA, Megurine Luka, Hatsune Miku, Meiko, Kaito, and Kagamine Rin.