John Lewis Coster (1838 – 17 December 1886) was a 19th-century member of parliament from Christchurch, New Zealand.
He quickly rose to leading positions and the management of the Union Bank of Australia sent him to Christchurch in March 1859.
There, he transferred to the Bank of New Zealand and became manager of the branch in Christchurch.
On Coster's initiative, the New Zealand Shipping Company was founded in 1873, and he was its managing executive for many years.
Since he returned from a business trip to London in March 1886, he was unable to work, and he died on 17 December 1886 at his residence in Opawa at the age of 48.