Williamstown is a suburb of Melbourne, Victoria, Australia, 8 km south-west of Melbourne’s central business district in the local government area of the City of Hobsons Bay.

Williamstown is a largely residential suburb on the western side of Port Phillip Bay, with a commercial and recreational waterfront precinct. It is the second-oldest suburb in Victoria, and the first to be settled in Melbourne.

Williamstown was named after William IV of the United Kingdom and was established in 1837, two years after Melbourne. It was initially a major port and the centre of the trade in the Port Phillip district. It later became a popular seaside resort and is now a residential suburb with a significant historic precinct.

The suburb is characterised by its historic streetscapes, with many buildings dating back to the 1850s. It is home to a number of heritage-listed sites, including the Williamstown Botanic Gardens, the Williamstown Town Hall, the Williamstown Railway Station, and the Williamstown Naval Dockyard.

Williamstown is well-serviced by public transport, with a number of bus routes and a train station. It is also close to the West Gate Freeway, providing easy access to the city and other suburbs