The snake on Metallica's self-titled 1991 album cover is derived from the Gadsden flag.
The cover places a coiled snake in the lower-right corner and the band's logo in the upper-left. On the original release, both emblems were embossed against a black background, making them deliberately difficult to see.
The Gadsden flag is associated with a coiled rattlesnake and the motto “Don't Tread on Me.” That motto also appears as the title of a song on Metallica, creating a direct visual and thematic connection between the packaging and the track list.
Later editions made the logo and snake dark gray, so they stand out more clearly. The cover has also been compared jokingly with other black rock-album artwork, including Spinal Tap's fictional Smell the Glove.