Trivia

During the 1970s served as a great "ham-fisted" foil to Clint Eastwood, appearing in four of Eastwood's films: La sanction (1975), Doux, dur et dingue (1978), Le Canardeur (1974) and Joe Kidd (1972). Usually Eastwood would pummel Walcott to a bloody pulp by the end of the picture.

Greg was introduced to his wife Barbara at a party by Hollywood legend, Dale Evans. Greg and Barbara had been married for 55 years when Barbara passed away on June 14, 2010.

When he met Ava Gardner, he informed her that they came from the same hometown.

Father of Todd Mattox, puppeteer on Men in Black (1997) and Men in Black 2 (2002).

Interviewed in "It Came from Horrorwood: Interviews with Moviemakers in the SF and Horror Tradition" by Tom Weaver (McFarland, 1996).