Wagin /ˈweɪdʒɪn/ is a town and shire in the Wheatbelt region of Western Australia, approximately 225 km (140 mi) south-east of Perth on the Great Southern Highway between Narrogin and Katanning. It is also on State Route 107. The main industries are wheat and sheep farming.

The name of the town is derived from Wagin Lake, a usually dry salt lake south of the town. The lake's name is of Noongar origin, and was first recorded by a surveyor in 1869–72. It means "place of emus", or "site of the foot tracks from when the emu sat down".

The first European explorer through the area was John Septimus Roe, the Surveyor General of Western Australia, in 1835 en route to Albany from Perth. Between 1835 and 1889 a few settlers eked a simple living by cutting sandalwood and shepherding small flocks of sheep. Land was granted to pastoralists in the Wagin area from the late 1870s.

The town itself came into existence after the construction of the Great Southern Railway, which was completed in 1889, with the town originally called Wagin Lake.

The first post office and telegraph building, designed by George Temple-Poole, was completed in 1893. The building was replaced by the current building in 1912. The building was designed by Hillson Beasley and built at a cost of £2,596; the old building was converted to living quarters.

The local Agricultural Hall was built by 1896 and opened 1 December the same year. In 1898 Wagin was proclaimed a town with the word Lake dropped. A further railway connection with the Collie to Narrogin line at Bowelling, the Wagin to Bowelling railway line, was made on 10 December 1918.

In early 1898 the population of the town was 175: 125 men and 50 women.

Saint George's Anglican church, a stone Federation Gothic style stone building with a tower, was constructed in 1900 on land donated by Frederick Piesse.