Martin Johannes Walser (German: [ˈmaʁ.tiːn ˈvalˌzɐ] ^ⓘ; 24 March 1927 – 26 July 2023) was a German writer, known especially as a novelist. He began his career as journalist for Süddeutscher Rundfunk, where he wrote and directed audio plays. He was a member of Group 47 from 1953 on.

His first novel, Marriage in Philippsburg, a satirical portrait of postwar society, became a success in 1957. Walser then turned to freelance writing. He published a trilogy of novels about the character Anselm Kristlein, beginning with Halbzeit in 1960, Das Einhorn (The Unicorn) in 1966 and ending with Der Sturz (The Fall) in 1973. Most of his major works have been translated into English, including the 1978 novella Runaway Horse, which was successful with both readers and critics. He also wrote plays (Die Zimmerschlacht), screenplays, story collections and essays. Several of his books have been adapted to the screen, including Runaway Horse in 1986 and again in 2007.

Walser received many awards, including the Georg Büchner Prize in 1981 and the Peace Prize of the German Publishers' Association in 1998. His acceptance speech for the Peace Prize caused controversy with Walser's remarks on German commemoration of the Holocaust. The "monumentalization of shame", he said, risks turning remembrance of the Holocaust into a "lip service" ritual. In 2002, Walser's portrayal of the literary critic Marcel Reich-Ranicki in his novel Tod eines Kritikers [de] ("Death of a Critic") was regarded as anti-Semitic.

Walser is regarded, along with Heinrich Böll, Günter Grass, and Siegfried Lenz, as one of Germany's most influential postwar authors.

Walser was born on 24 March 1927 in Wasserburg, on Lake Constance. His parents were coal merchants who also kept an inn next to the train station in Wasserburg. The second of three children, Walser lost his father at age ten. He described the environment in which he grew up in his novel A Gushing Fountain. From 1938 to 1943 he attended the secondary school in Lindau, until his induction to the armed forces, initially as an anti-aircraft auxiliary. According to documents released in June 2007, he became a member of the Nazi Party on 20 April 1944 at age 17. Walser denied that he knowingly entered the party, and assumed that he was enrolled by a garrison commander as part of a larger group without his knowledge. The claim was disputed by Hans-Dieter Kreikamp from the German Federal Archives, who said that a personal signature was formally required, even in times of war. By the end of the Second World War, Walser was a soldier in the Wehrmacht.

After the war, he completed his Abitur in Lindau in 1946. He then studied literature, history, and philosophy at the University of Regensburg and the University of Tübingen, achieving his doctorate in literature in 1951 with a thesis on Franz Kafka.

While studying, Walser worked as a reporter for the Süddeutscher Rundfunk broadcasting company, and wrote and directed his first audio plays. He travelled to Czechoslovakia, England, France, Italy, and Poland as part of his job. In 1950 Walser married Katharina "Käthe" Neuner-Jehle; the couple had four daughters.

Beginning in 1953, Walser was regularly invited to conferences of the Group 47, which was focused on literature for a new democratic Germany. The group awarded him a prize for his story Templones Ende in 1955. His first novel, Marriage in Philippsburg, was published in 1957. Like his later books, it was set in Southern Germany in a postwar society, and satirically portrayed the "conservative middle class" during the "so-called economic miracle". The novel first appeared in English three years later as The Gadarene Club.