The Dean Single, 3031 Class, or Achilles Class was a type of steam locomotive built by the British Great Western Railway between 1891 and 1899. They were designed by William Dean for passenger work. The first 30 members of the class were built as 2-2-2s of the 3001 Class. In 1900, George Jackson Churchward replaced the boiler on number 3027 Worcester with a parallel Standard 2 boiler. Twelve further engines were similarly converted in 1905 and 1906.