What does the snake on Metallica's Black Album cover come from?

The snake on Metallica's Black Album cover comes from the Gadsden flag.

The cover shows Metallica's logo in the upper-left corner and a coiled snake in the lower-right. The snake is derived from the Gadsden flag, an American Revolutionary-era symbol associated with the motto “Don't Tread on Me.” That same motto became the title of a song on the album.

The first edition used an especially understated design: the logo and snake were embossed so they were difficult to see against the black background. Later editions made the emblems dark gray, increasing their visibility while preserving the minimalist concept.

The cover also prompted a humorous comparison with the fictional album Smell the Glove from the film This Is Spinal Tap. Metallica acknowledged the resemblance in the documentary A Year and a Half in the Life of Metallica.