USS Excalibur (NCC-1705)
The USS Excalibur (NCC-1705) was an Constitution class vessel in service in the 23rd century. (Star Fleet Technical Manual)
USS Excalibur (NCC-2004)
The USS Excalibur (NCC-2004) was an Excelsior-class vessel constructed around the turn of the 24th century. (FASA RPG: Star Trek: The Next Generation Officer's Manual)
USS Excalibur (NCC-26517)
See USS Excalibur (NCC-26517).