Nikiforos Vrettakos, 79, one of Greece's best-known poet and the first leftist member of the Athens Academy of Arts and Sciences, died in Athens Sunday of a stroke. He published his first book in 1929. It was followed by scores of collections of emotionally charged, simply written verse. He twice won the country's prestigious State Poetry Prize and his work was translated into several languages. Many of his poems were set to music. He wrote about his experiences as a soldier during World War II and about the plight of the left after losing the 1946-1949 civil war. He accepted the nomination to the Athens Academy in 1988.