Thomas Ahearn, PC (June 24, 1855 – June 28, 1938) was a Canadian inventor and businessman. Ahearn, a native of Ottawa, Canada West, was instrumental in the success of a vast streetcar system that was once in Ottawa, the Ottawa Electric Railway, and was the first chairman of Canada's Federal District Commission in 1927. He held several patents related to electrical items and headed companies which competed for decades with Ottawa Hydro as providers for electricity in Ottawa. Ahearn co-founded the Ottawa Car Company, a manufacturer of streetcars for Canadian markets.