PS Zealous was a passenger vessel built for the Great Eastern Railway in 1864.

[1] The ship was built by the J & W Dudgeon of Cubitt Town, London for the Great Eastern Railway and launched on 23 April 1864.

[2] She was launched by Miss Alice Goodson, eldest daughter of the chairman of the Great Eastern Railway Company.

Zealous was the first of a trio of new vessels, and inaugurated the GER's passenger services from Harwich to both Rotterdam and Antwerp in 1865, later joined by Avalon and Ravensbury.

[3] Zealous was altered in 1866 to carry cargo as well as passengers, and she was re-boilered in 1873.