Skull and Bones is an undergraduate senior secret society at Yale University, New Haven, Connecticut. It is the oldest senior class landed society at Yale.
The society's alumni organization, which owns the society's real property and oversees the organization, is the Russell Trust Association, named for William Huntington Russell, who co-founded Skull and Bones with classmate Alphonso Taft. The Russell Trust was founded by Russell and Daniel Coit Gilman, member of Skull and Bones and later president of the University of California, first president of Johns Hopkins University, and the founding president of the Carnegie Institution.
The society is known informally as "Bones", and members are known as "Bonesmen".