Joseph Roos (1908-1999) was a pioneering community relations adviser and activist who helped to infiltrate the prewar Nazi movement in Los Angeles. Roos was born in Vienna, Austria, and came to the United States in 1928. He became a Chicago newspaperman during the height of the Depression and in 1933 worked with George C. Marshall to launch the first government investigation of Nazi activities in America.

Roos came to California in 1934 to work in book publishing and wound up working as a publicist for Universal Pictures. He later became a story editor at United Artists and RKO Studios. In 1938, Roos began working with the Jewish Community Committee, which became the Community Relations Committee of the Jewish Federation Council. The pro-Nazi German American Bund, a national organization, arose in Los Angeles in the 1930s around the same time Adolf Hitler gained power. Roos took a leading role in investigations that would expose white supremacy groups and help to arouse the local Jewish community to the seriousness of the Third Reich's threat. Under the leadership of the Hitler-appointed American Fuhrer, Fritz Kuhn, the Bund tried to organize boycotts of Jewish-run businesses, especially those in the movie industry. Ultimately, the Bund hoped to purge the United States of Jews, minorities, Communists, and anyone who did not share its notion of Aryan supremacy.

Roos went on to serve as executive director of the Committee from 1945 to 1969, when he retired. In his work with the Committee, Roos gained a national reputation as a pioneer in the fields of race and community relations. In 1969 he started his own firm, Community Relations Consultants, and in 1984, Roos helped form USC's Office of Civic and Community Relations, the university's community outreach arm. He continued to advise USC on community relations matters until 1993. Roos was honored in 1979 by USC's School of Journalism with its Distinguished Achievement in Journalism Award. In 1997 at USC's second annual Jewish Community Luncheon, President Steven B. Sample awarded Roos a Lifetime Achievement Award for his service to the Southern California Jewish community. Roos was also a founder and board member of the Pacific Coast Council in Inter-Cultural Relations and of the Los Angeles County Commission on Human Relations.