Medlock died Oct. 31 of bladder cancer at Brotman Medical Center in Culver City, said her only child, Linda Medlock-Jackson.
"I feel like I'm Jack in the beanstalk fighting a giant," Medlock said in The Times in 1985 while fighting a city plan to place a huge trash incinerator near her South Park home.
With Medlock often leading the charge, newly organized community members spoke up at public meetings and forced the city to abandon the project.
Environmentalist Ellen Stern Harris wrote in The Times in 1987: "City Hall has seldom seen such effective community organizing."
The upset victory sparked a wave of grass-roots political activity directed toward reviving the area. The South East Central Homeowners Assn. that Medlock helped found and lead was at the movement's center.
Councilwoman Jan Perry, who represents South Park, called Medlock "intelligent and fierce."
"She loved South Park . . . and left her imprint on her community in an unforgettable way," said Perry, who publicly recognized Medlock's community activism last year.
When Medlock and her husband bought their South Park bungalow in 1953, they became part of a prosperous working-class neighborhood of blacks.
Rep. Maxine Waters (D-Los Angeles), whose district includes South Park, said in a statement that she was fond of listening to Medlock reminisce about "when South Park was the center of the community, and when families slept out in the park on hot summer nights."
When many middle-class blacks moved out after the 1965 Watts riots, Medlock stayed put in her home near 49th Street and Avalon Boulevard.
In her Southern accent, she spoke out against "land grabbers" who she feared would tear down single-family homes and replace them with low-rent apartments for the neighborhood's Latino immigrants.
She also fought to save her neighborhood from a proposed freeway and rail lines, Medlock said in The Times in 1994.
"You could not help but love her even when she was cantankerous and confrontational; she didn't hesitate to speak her mind," Waters wrote. "She was the voice prepared to deal with City Hall, the police department, the school district and anyone else."
She was born Lois Ethel Metcalf on Feb. 14, 1926, in Caddo Parish, La., the fourth of five children of a farmer.
When she was about 10, her family moved to Dallas, where she graduated from high school and met her future husband, James Earl Medlock.
In 1945, the couple moved to Los Angeles, where her husband worked for a wholesale meat company. He died in 1994.
For years, Medlock designed clothes and artistic pieces -- burlap roses, bottled art, area rugs -- that she sold.
With a tam on her head and a walking staff in her hand, Medlock would implore others, as she did in 1994: "We must come together as human beings and together make things happen."
In addition to her daughter, Medlock is survived by a grandson and three great-grandsons.
Nelson is a Times staff writer.