3820 (pronounced Thirty-eight twenty) is a 4-6-2 steam locomotive operated by the New South Wales Government Railways between 1947 and 1970.

[1] During the rundown of steam operation in New South Wales, 3820 had the distinction of some lasts:[1][2] Upon withdrawal, 3820 was placed in the custody of the New South Wales Rail Transport Museum and based at Enfield Locomotive Depot operating excursion trains including a journey to Melbourne with 3801, and the Last Run which it triple headed with 3203 and 3526 to Tarana on 21 April 1973 before the Public Transport Commission banned main line steam operation.

[1][2] 3820 was steamed on 1 January 1975, to act as a standby for 3801, which was used to haul fundraising trains for Cyclone Tracy survivors.

[2] In June 1975, it hauled 4001 and 2419 to Thirlmere when the New South Wales Rail Transport Museum relocated.

In 1980 it was hauled to Central station for display at an event commemorating 125 years of rail operations in New South Wales.