The South Eastern and Chatham Railway (SECR) O Class and its rebuild, the O1 Class was a class of 0-6-0 steam locomotives designed for freight work.
One O1 class, SECR No. 65 (SR No. 1065 , BR No. 31065) has been preserved on the Bluebell Railway in Sussex. This locomotive was built for the South Eastern Railway (SER) in 1896, before the 1899 amalgamation into the South Eastern and Chatham Railway. It is the only surviving SER locomotive.