Marcella Nicholas Leach (August 15, 1929 – March 16, 2015) was an American victims' rights advocate based in Southern California and the mother of technology entrepreneur and victims' rights leader Henry Nicholas.
After the murder of her daughter, Marsalee (Marsy) Nicholas in 1983, she helped build Justice for Homicide Victims, one of California's early victims' rights organizations.
Her late daughter is the namesake for Marsy's Law, the California Constitutional Amendment and Victims' Bill of Rights, which appeared on the November, 2008, ballot as Proposition 9.