Montague Stanley Napier (14 April 1870 – 22 January 1931) was an English automobile and aircraft engine manufacturer. His grandfather, David Napier (1785–1873), had moved to London from Scotland and by 1836 had established an engineering company in Lambeth called D. Napier & Son. Montague Napier bought the business from the executors of his father's estate in 1895, and diversified into producing machine tools for the cycle industry.

Following a meeting with businessman and racing driver Selwyn Edge in 1899 Napier diversified into automobile manufacturer, and for a time his company was the leading supplier of luxury cars in the British market. His focus switched from cars to aircraft engines after the outbreak of the First World War in 1914, and he developed the very successful Lion engine.

Napier's health broke down in 1915 and he chose to move to the south of France, but he continued to work as a design consultant for his company. He died at his home in Cannes on 22 January 1931, aged 60.