The USS Archon was a Federation starship that was in service during the mid-22nd century. In 2167, the Archon disappeared while investigating the planet Beta III.
Its fate would remain a mystery for a hundred years, until the USS Enterprise visited that planet in 2267, and learned that the sapient computer Landru had destroyed the ship, and murdered or absorbed her crew. The Archon's visit became an apocryphal tale to the Betans, who mixed it in with their quasi-worship of Landru; her crew became known as Archons. (TOS: "Return of the Archons")
Background
According to the Star Trek Encyclopedia this vessel is a Daedalus-class starship, with the registry NCC-189.
In canonical Star Trek, the prefix U.S.S. is not associated with this starship. This prefix is seen in non-canonical works like the Star Trek Encyclopedia and the Star Trek Concordance.