John Ostashek (May 10, 1936 – June 10, 2007) was a Yukon politician. An entrepreneur, he was elected leader of the Yukon Party in June 1992 and led it to victory in the fall 1992 election in which he also won a seat in the legislature for the first time. Ostashek's Yukon Party lost the 1996 election to the Yukon NDP though he retained his seat and became leader of the opposition. In the 2000 election however his Yukon Party was again defeated, this time by the Liberals with Ostashek losing his own seat. He subsequently resigned as Yukon Party leader and retired from politics.