Quattrone plans to retire Sept. 1 to Charleston, S.C., where his wife already lives much of the year and where his adult daughter is a teacher. (His son works in marketing for Chevrolet in Detroit.)
"John has played a crucial role in the development of GM's senior leadership team as well as serving as a trusted adviser and counselor on many important issues across the company," Barra said. "In addition, he's been a big part of the cultural transformation that has occurred at GM over the past several years."
GM interviewed numerous candidates to succeed Quattrone before settling on Tomas, who left Anthem in April after three years. The company, headquartered in Indianapolis and previously known as WellPoint, had 53,000 employees at the end of last year, about one-fourth as many as GM.
Tomas, who holds degrees in business administration and human resource management from Florida International University, spent nine years at Burger King, playing a "crucial role" in improving the fast-food giant's culture during several transitions between public and private ownership, GM said. He previously had various human resources jobs at the transportation logistics company Ryder Systems and at Publix Super Markets.
Tomas -- GM's fourth new human resources boss since Barra held that role from 2009 through 2011 -- will start at GM on July 1, working with Quattrone for two months before taking over the job.