What nickname came from the nearly black cover of Metallica's 1991 self-titled album?

The nearly black cover of Metallica's 1991 self-titled album produced the nickname The Black Album.

The official album title is Metallica, an eponymous name that keeps the wording deliberately simple. On the original cover, the band's logo and a coiled snake are embossed so subtly against the black background that they are difficult to see.

The snake is derived from the Gadsden flag, whose motto, “Don't Tread on Me,” also gives one of the album's songs its title. The cover's restrained design helped create a visual identity distinct from the detailed artwork on several earlier Metallica records.

Later editions used dark gray emblems that stand out more clearly, but the nickname remained. It is therefore a widely used informal title, not the album's official name.