Mary Jo Slater, CSA (born 19 April 1946; age 78), née Mary Jo Lawton, was the casting director for Star Trek VI: The Undiscovered Country. She is also the mother of actor Christian Slater. Being the casting director for Star Trek VI, Slater was able to get her son, a Star Trek fan, a brief cameo in that film.
A member of the Casting Society of America, Slater has also served as casting director for such films as Body of Evidence (1993, in which she worked with Mark Rolston, Richard Riehle, and Frank Langella) Ace Ventura: Pet Detective (1994, with Noble Willingham, Mark Margolis, and Bill Zuckert), In the Army Now (1995, with Andy Dick, Lori Petty, and Glenn Morshower), Murder in the First (1995, working with her son, Christian, as well as Brad Dourif), Spawn (1997), The Contender (2000, also with her son, as well as Saul Rubinek), The Amati Girls (2000, with Paul Sorvino, Matt Winston, and Robert Picardo), and The Last Castle (2001). She also worked on 12 Angry Men (1997) and Inherit the Wind (1999).
She has received Emmy nominations for Outstanding Casting for Traffic (2004) and Elvis (2005). She also did casting for One Life to Live, the TV drama In the Heat of the Night, Walker, Texas Ranger (featuring Noble Willingham), Babylon 5 (starring Claudia Christian, Andreas Katsulas, Bill Mumy, and Mary Kay Adams) and Stargate SG-1.