The Puffing Billy Railway is a 2 ft 6 in (762 mm) narrow gauge heritage railway in the southern foothills of the Dandenong Ranges in Melbourne, Australia. The railway was one of the five narrow gauge lines of the Victorian Railways which opened around the beginning of the 20th century. It is close to the city of Melbourne and is one of the most popular steam heritage railways in the world, attracting tourists from Australia and overseas. The railway aims to preserve and restore the line and its operation as closely as possible to the way it was in the first three decades of its existence, but with particular emphasis on the early 1920s.

The starting point of the railway is Belgrave station which houses the railway's operations and administration centre. The line runs through Lakeside Station where a visitor information centre provides catering and an indoor interpretive space, and terminates at Gembrook railway station.

In 2022, passengers were allowed to resume the popular practice of sitting on the window ledges of carriages with their legs dangling outside, which had become a core part of the charm of the railway.