Neptune was a merchant ship built at Chepstow, Wales in 1836.

She made one voyage transporting convicts from Ireland to Australia.

Neptune first appeared in Lloyd's Register (LR) in 1836.

On her only convict voyage, under the command of Joseph (or Jeremiah) Nagle and surgeon Patrick Martyn, she departed Dublin, Ireland on 27 August 1837, and arrived in Sydney on 2 January 1838.

Her cargo consisted of 47 tons of copper ore, 725 bales of cotton, 79 tons of Nicaragua wood, 19 bales of wool, 132 pieces of copper, and eight seal skins.