Massive Attack is a British trip-hop band. Their music crosses many genres but is something like a mix of electronic, dub, and hip-hop music. Massive Attack's music is highly melodic with dark undertones. Their vocals are often soulful female singing or mellow male rap vocals. Their instrumentals are often downtempo and rhythmic with an ambient atmosphere. Massive Attack's first full album, Blue Lines, was well received and popularized the trip-hop genre in 1991. The group is composed of Andrew "Mushroom" Vowles, Grant "Daddy G" Marshall, and Robert del Naja "3D". Their tracks often feature a wide variety of guest artists, most notably Horace Andy and Sinéad O'Connor.