Sir Lewis Cohen (23 December 1849 – 24 June 1933) was a businessman who was a Member of the South Australian Parliament for 10 years and served on the Adelaide City Council for 30 years. He was Mayor of Adelaide from 1889–1890, 1901–1904, and 1909–1911, and then Lord Mayor from 1921–1923. He was knighted in 1924.
Cohen was born in Liverpool, where his father had a clothing business. At age two he was taken with his family to Sydney to set up business there. Nine years later with the business running successfully, the family returned to England, and Lewis was sent to Jewish school at Edmonton. At age 17 he returned to Sydney and at 19, bankrolled by his father and accompanied by a friend, he set up a shop in Levuka, then capital of Fiji. He took part in public affairs there, and was elected to Levuka's first council in 1872. With his health failing, he returned to Sydney in 1873, where he remained until 1876 when on medical advice he and his wife moved to Adelaide, opening a branch of the London Discount Bank.
He married Selina Marks (6 March 1856 – 16 October 1933) in Melbourne on 9 April 1873. Their children were:
A north-south road through the south park lands of Adelaide linking to Greenhill Road, South Terrace and Morphett Street is named in his honour.