Harry Gold (born Henrich Golodnitsky, December 11, 1910 – August 28, 1972) was a Swiss-born American laboratory chemist who was convicted as a courier for the Soviet Union passing atomic secrets from Klaus Fuchs, an agent of the Soviet Union, during World War II. Gold served as a government witness and testified in the case of Julius and Ethel Rosenberg, who were convicted and executed in 1953 for their roles. Gold served 15 years in prison.

Born in Bern, Switzerland, to parents from the Russian Empire, Gold immigrated to the US with his parents as a child at the age of four and settled in Philadelphia. During the Great Depression, he found work and finished his degree in chemistry at night. He returned to work as a clinical chemist after release from prison.

Heinrich Golodnitsky was born on December 11, 1910, in Bern, Switzerland to Samson and Celia (Ominsky) Golodnitsky, both Jewish immigrants from what is now Ukraine and was then part of the Russian Empire. Samson had grown up in Smila, where his father was a successful merchant. He was sent to Switzerland for additional schooling, as opportunities for Jews were limited in Russia, but he was influenced by reading Leo Tolstoy and chose to go into woodworking. He became a carpenter. Henrich's mother, Celia, first emigrated from central occupied Ukraine (annexed lands of the Russian Empire) as a teenager to Paris, where she studied dentistry. She supported the Zionist movement. After running out of money, she took a job in a cigar factory in Bern, where she met Samson. They married around 1907 or 1908.

When Heinrich was 4, his family immigrated to the United States, seeking more opportunity. After they arrived at New York in July 1914, an agent at Ellis Island suggested they shorten their surname to Gold, to which they agreed. In the United States, the boy became known as Harry. They first went to Chicago, where Sam worked in a coalyard and Celia in a tobacco factory, both limited by their lack of English. After a year, they left. Sam went to Norfolk, Virginia, where he had some relatives. Celia took their son to Philadelphia, where her brother Shama had settled. When the shipyard job and conditions in Norfolk did not work out, Sam joined them in Philadelphia, a major industrial city. They settled in South Philadelphia in 1915 in the Jewish section. Ethnic Irish occupied territory to the north, and Italians to the west. After some other jobs, Sam found work as a cabinetmaker at the Victor Talking Machine Company in Camden, New Jersey, across the Delaware River.

In 1917, Gold’s mother had another son, named Yussel (Joseph), after a grandfather. Neighbors on Philip Street later described the Gold family as unusually quiet and stand-offish, but Harry Gold said he had a happy and secure childhood. He greatly enjoyed learning and was a good student in school. To supplement Sam's modest earnings, Celia taught Hebrew and Yiddish to neighborhood children, and was considered an excellent teacher. She expanded the lessons with Jewish folklore and Hebrew literature.

In the early 20th century, immigrant groups in Philadelphia clashed over territory. As a boy in the neighborhood, Gold suffered from this, especially since he was small and slight and non-athletic. His father complained of discrimination by newly hired Italian immigrants at the Victor Company, where he was one of the few Jews. In the mid-1920s, an Irish foreman tried to drive him out of the factory, but he persisted. Gold admired his father's stoicism but resented the conflicts, and this experience developed a desire in him to fight prejudice. He had an early interest in chemistry and graduated from South Philadelphia High School in 1929.

After high school graduation, Gold was offered a job by one of his father’s acquaintances at Giftcrafters, a woodworking firm in the northern Kensington section of the city.

While seeking other positions, Gold found employment at the Pennsylvania Sugar Company. Employment there provided economic security and the opportunity to work with college-educated chemists in state-of-the art labs. He saved money from his work and attended the University of Pennsylvania full time from 1930 to 1932 before his money ran out. The Great Depression was unfolding, and he returned to Pennsylvania Sugar to help his family.