The South African Railways Class 1 4-8-0 of 1904 was a steam locomotive from the pre-Union era in the Colony of Natal. In 1904, the Natal Government Railways placed fifty Class B 4-8-0 Mastodon type steam locomotives in service. Six of them were modified to a 4-8-2 Mountain type wheel arrangement in 1906. In 1912, when the remaining 44 4-8-0 locomotives were assimilated into the South African Railways, they were renumbered and designated Class 1.