Crystal's best known films include the 1989 comedy When Harry Met Sally
Actor Billy Crystal has been named as a director for the organisation set up to raise funds to build a memorial to victims of the 11 September attacks.
The 60-year-old joins the board of the National September 11 Memorial and Museum foundation, alongside former Analyze This co-star Robert De Niro.
The New York site will include two waterfalls where the twin towers of the World Trade Centre previously stood.
Crystal took part in a 9/11 benefit concert a month after the 2001 attacks.
'Strength and resolve'
The event, which also featured Sir Paul McCartney, David Bowie and Sir Elton John, raised more than $35m (£17.5m) for families of those who died in the terror attacks.
Crystal said he was "honoured" to join the organisation and have the opportunity to "contribute to the creation of a permanent national memorial".
The star, who was born in New York, added that the project was "an opportunity to demonstrate New York's strength and resolve, whilst ensuring that the memories of the lives lost are never forgotten".
So far the foundation has raised more than $350m (£175.7m) from private funds towards the memorial.
The design for the landscaped site is called Reflecting Absence, and will have the names of the 2,980 people who were killed in the attacks inscribed along the edges of the pools.
The museum will include personal effects and the testimonies of witnesses to the events of 11 September 2001.
The site is due to open in 2009.