Justin Warren Marshall (born 5 August 1973) is a New Zealand former rugby union player.

He was born in Gore on 5 August 1973 and educated at Gore High School, before settling in Christchurch where he played for the High School Old Boys club.

It was whilst here that Marshall first made the break into the All Blacks side for the 1995 tour of Italy and France.

In 1997 Marshall was made captain of New Zealand and led out his team in four tests in Great Britain and Ireland, becoming the All Blacks' 54th test captain.

In moving to Europe, Marshall retired from international rugby with the All Blacks in 2005.

His New Zealand contract ran out after the 2005 Lions tour, and he signed to play the 2005–06 season for Leeds Tykes in the English Premiership.

On 25 April 2006 it was announced he had signed for the Welsh regional side Ospreys on a two-year contract beginning in September 2006.

On 16 July 2008 Ospreys announced that Marshall had been released from his contract early, and he signed for Top 14 side Montpellier.

On 15 January 2009 he signed for Saracens on a contract to the end of the 2008–09 season.

In April 2013, Marshall made an unexpected comeback, taking the field for club side Wakatipu, at the age of 39.

Marshall joined Sky TV New Zealand in 2010.

In the 2005 Queen's Birthday Honours, Marshall was appointed a Member of the New Zealand Order of Merit, for services to rugby.