Jessica Alba, Gerard Butler for 'CNN Heroes'

Jessica Alba and Gerard Butler have signed on to appear on the CNN Heroes: An All-Star Tribute telecast on Thanksgiving night.

According to CNN's Marquee Blog, the two Hollywood stars will help to honour ten specially selected "heroes" that have made a difference in their local communities.

Demi Moore, Halle Berry, Kiefer Sutherland and Renee Zellweger are also scheduled to take part in the special broadcast.

Musical performers will include Bon Jovi, Common, Sugarland and John Legend.

Anderson Cooper is to host the fourth annual CNN Heroes: An All-Star Tribute, which airs on November 25 from 8pm ET on CNN.