Hawthorn Leslie and Company was a British engineering firm established in 1820, primarily known for manufacturing locomotives and railway equipment. The company played a significant role in the development of the railway industry during the 19th century, producing a variety of steam engines and rolling stock for both domestic and international markets. Based in Newcastle upon Tyne, Hawthorn Leslie expanded its operations over the years, eventually becoming a key player in the locomotive manufacturing sector. The company merged with other firms and continued to operate until the mid-20th century, contributing to the evolution of railway technology and infrastructure.