Robert H. Levenson, an advertising executive who helped produce some of the mid-20th century’s most memorable campaigns, writing evocative advertisements for clients like Volkswagen, El Al and Sara Lee, died on Wednesday at his home in Manhattan. He was 83. Mr. Levenson was associated for more than a quarter-century with the New York agency Doyle Dane Bernbach. He became the agency’s creative director in 1970 and was later a vice chairman and the chairman of its international operation.