Patrick Joseph Lynch (24 May 1867 – 15 January 1944) was an Australian politician who served as a Senator for Western Australia from 1907 to 1938.

He migrated to Queensland in 1886 and cut railway sleepers near Charleville and then travelled to the Croydon goldfields.

In 1888 he started to work on ships operating along the Australian coast and in the South Pacific, eventually qualifying as a marine engineer.

He worked as an engineer on a sugar plantation in Fiji and then on the Kalgoorlie goldfields in Western Australia.

During World War I, he was the first Federal Labor parliamentarian to advocate conscription and along with Billy Hughes, stopped attending the parliamentary caucus of the party on 14 November 1916.