August Landmesser (born 24 May 1910; missing and presumed dead 17 October 1944; declared dead in 1949) was a worker at the Blohm + Voss shipyard in Hamburg, Germany, best known for his appearance in a photograph refusing to perform the Nazi salute at the launch of the naval training vessel Horst Wessel on 13 June 1936.

August Landmesser was the only child of August Franz Landmesser and Wilhelmine Magdalene (née Schmidtpott).

In 1931, hoping it would help him get a job, he joined the Nazi Party.

In 1935, when he became engaged to Irma Eckler (a Jewish woman), he was expelled from the party. They registered to be married in Hamburg, but the Nuremberg Laws enacted a month later prevented it.

On 29 October 1935, Landmesser and Eckler's first daughter Ingrid was born.

A now-famous photograph, in which a man identified as Landmesser refuses to give the Nazi salute, was taken on 13 June 1936.

In 1937, Landmesser and Eckler tried to flee to Denmark but were apprehended.

She was again pregnant, and he was charged and found guilty in July 1937 of "dishonoring the race" under Nazi racial laws.

He argued that neither he nor Eckler knew that she was fully Jewish, and was acquitted on 27 May 1938 for lack of evidence, with the warning that a repeat offense would result in a multi-year prison sentence. The couple publicly continued their relationship.

On 15 July 1938 he was arrested again and sentenced to two and a half years in the concentration camp Börgermoor.

Eckler was detained by the Gestapo and held at the prison Fuhlsbüttel, where she gave birth to a second daughter Irene. From there she was sent to the Oranienburg concentration camp, then the Lichtenburg concentration camp for women, and then the women's concentration camp at Ravensbrück. Their children were initially taken to the city orphanage. Ingrid was later allowed to live with her maternal grandmother; Irene went to the home of foster parents in 1941.

After her grandmother's death in 1953, Ingrid was also placed with foster parents.

A few letters came from Irma Eckler until January 1942. It is believed that she was brought to the so-called Bernburg Euthanasia Centre in February 1942, where she was among the 14,000 killed; in the course of post-war documentation, in 1949 she was pronounced legally dead, with a date of 28 April 1942.

Meanwhile, Landmesser was discharged from prison on 19 January 1941. He worked as a foreman for the firm Püst, a haulage company. The company had a branch at the Heinkel-Werke (factory) in Warnemünde.

In February 1944 he was drafted into a penal battalion, the 999th Fort Infantry Battalion.

He was declared missing in action, and presumed killed during fighting in Croatia on 17 October 1944. Like Eckler, he was declared legally dead in 1949.

The marriage of August Landmesser and Irma Eckler was recognized retroactively by the Senate of Hamburg in the summer of 1951, and in the autumn of that year Ingrid assumed the surname Landmesser. Irene continued to use the surname Eckler.

In 1996, Irene Eckler published the book Die Vormundschaftsakte 1935–1958 : Verfolgung einer Familie wegen "Rassenschande" (The Guardianship Act 1935–1958: Persecution of a Family for "Dishonoring the Race"). This book about the story of her family includes a large amount of original documents from the time in question, including letters from her mother and documents from state institutions.

A figure identified as August Landmesser is featured in a photograph taken on 13 June 1936, published on 22 March 1991 in Die Zeit.

It shows a large gathering of workers at the Blohm + Voss shipyard in Hamburg, for the launching of the navy training ship Horst Wessel.

Everyone in the image has raised his or her arm in the Nazi salute, with the exception of a man toward the back of the crowd, who grimly stands with his arms crossed over his chest.

Whether the depicted man is Landmesser is not known with certainty; requests to definitively identify him not been answered and his daughter Irene is unsure.