His acting career began on the repertory stage in 1920, eventually becoming a member of the Vienna Volkstheater and went on to earn a sturdy reputation as a dramatic performer both in his homeland and in Berlin. Like many other Austrian and German actors of his generation, he was forced to flee mainland Europe during the rise of Adolf Hitler and the Nazis in the late 1930s. He initially emigrated to England in 1933 where he appeared unbilled in a small number of productions including Carol Reed’s Night Train to Munich in 1940 – he played the uncredited role of the Concentration Camp Physician (pictured). His other two British films were Convoy (1940) as Commander Deutschland and Sailors Three (1940) as the German Captain.
His British acting career didn’t really take off and he subsequently emigrated to the USA. Described as a dark, cold-eyed, thin-lipped player with a precise, meticulous air about him, he found himself invariably playing the very characters he detested including appearances in such films as the Humphrey Bogart classic Sahara (1943), as well as The Boy from Stalingrad (1943), Dangerous Mists (1944) and Till We Meet Again (1944).
In post-war years, he was often spotted portraying ethnic professionals (scientists, doctors, professors, foreign royalty). Some of the higher quality roles he portrayed were Tomorrow Is Forever (1946); Count Von Papen in 5 Fingers (1952); and Ronchin in the musical Call Me Madam (1953). Although Wengraf never made it to the very top of the Hollywood character ranks, he remained a thoroughly strong and reliable player. In the 1950s and 1960s he transferred his talents to TV, appearing on a number of dramatic showcases and on such popular programs as The Untouchables (1959), Hawaiian Eye (1959), The Man from U.N.C.L.E. (1964) and The Time Tunnel (1966). His last few films included minor roles in the war-themed Judgment at Nuremberg (1961), Hitler (1962) and Ship of Fools (1965).
He retired in 1966, and died in 1974 in California.