Perth County is a county in the Canadian province of Ontario in Southwestern Ontario, 100 kilometres (62 mi) west of Toronto. Its population centres are Listowel, Mitchell and Milverton. The City of Stratford and the Town of St. Marys are within the Perth census division, but are separate from Perth County. The 2016 population of Perth County was 38,066.

Listowel is an unincorporated community in Ontario, Canada, located in the Municipality of North Perth. Incorporated as the Town of Listowel in 1875, it was dissolved in 1998 following amalgamation with several other communities in the northern section of Perth County. Its population was 9,539 at the Canada 2021 Census in a land area of 6.73 square kilometres; at the time there were 3,910 occupied dwellings.