Great Western Railway No. 36 was a prototype 4-6-0 steam locomotive constructed at Swindon Works in 1896, the first 4-6-0 ever built for the GWR and one of the first in Britain. It was designed by William Dean (engineer) and le Fleming comments that "the design is unusual and entirely Dean of the later period, including the only large boiler ever built entirely to his ideas."
No. 36 had double frames for the 4' 7+1/2" coupled wheels and an outside-frame bogie; cylinders were 20" x 24". The long boiler and raised round-topped firebox create a harmonious impression, and the loco acquired the nickname "The Crocodile". Among its innovative features included the use of Serve tubes. Designed for heavy freights through the Severn Tunnel, it proved itself exceptionally capable. It was probably due to Dean's declining state of health and Churchward's increasing influence that the loco did little work away from Swindon, remained a prototype, and was withdrawn by Churchward in 1905 with the low mileage of 171,428.
- le Fleming, H.M. (October 1954). White, D.E., ed. The Locomotives of the Great Western Railway, part seven: Dean's Larger Tender Engines. Kenilworth: RCTS. ISBN 0-901115-18-5.