The British Rail Class 33 also known as the BRCW Type 3 or Crompton is a class of Bo-Bo diesel-electric locomotives ordered in 1957 and built for the Southern Region of British Railways between 1960 and 1962.

A total of 98 were built by the Birmingham Railway Carriage and Wagon Company (BRCW) and were known as "Cromptons" after the Crompton Parkinson electrical equipment installed in them. Like their lower-powered BRCW sisters, the 26 and 27 classes, their bodywork and cab ends were of all steel construction. They were very similar in appearance to class 26/27 locos, but carried Southern Region two-digit headcode blinds between the cab windows.