Greif began his career as a NBC Page out of NBC-Burbank. He later was a producer with the television series Sins in 1986.
Greif's works include Walker Texas Ranger, Gene Simmons Family Jewels, Hatfields & McCoys, Brando, Funny Money, Mounted in Alaska, Meet Wally Sparks and Monday Night Mayhem. He has worked extensively in TV mini-series, reality television, full-length features and scripted television. Greif's production team includes Adam Reed, Adam Freeman, Herb Nanas, Joanne Rubino and Aaron Semmel at his production company ThinkFactory Media in Santa Monica. In 2012 Hatfields & McCoys, for which Greif was executive producer, won several Emmy Awards including Kevin Costner for best actor in a miniseries and Tom Berenger for best supporting actor.
- Robert Bauval; Ahmed Osman (26 July 2012). Breaking the Mirror of Heaven: The Conspiracy to Suppress the Voice of Ancient Egypt. Inner Traditions / Bear & Co. pp. 251–. ISBN 978-1-59143-813-7.
- "EMMYS: 'Hatfields & McCoys' Producer Leslie Greif" Nellie Andreeva Co-Editor-in-Chief, TV June 23, 2012 Deadline
- `Keys To Tulsa' Just Never Seems To Click - Philly.com
- Edmond Grant (1998). The Motion Picture Guide, 1998 Annual: The Films of 1997. CineBooks. ISBN 978-0-933997-41-7.
- Leonard Maltin (2 September 2014). Leonard Maltin's 2015 Movie Guide. Penguin Publishing Group. pp. 1251–. ISBN 978-0-698-18361-2.
- 10 Rules for Sleeping Around | Influx Magazine
- Interview: Producer Leslie Greif talks Historys [sic Hatfields & McCoys]
- One More Tango for Brando and His Golden Mumble. New York Times By VIRGINIA HEFFERNAN May 1, 2007
- Leslie Greif shingle relaunches as Thinkfactory | Variety
- "ITV: Global Entertainment Unit Preps New Dramas for International Market". Variety.