This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Zamzummim (Jewish)
Zamzummim, the name given by the Ammonites to the inhabitants of the Transjordanian territory whom they dispossessed . They were part of the nation of giants known as *Rephaim, who formed the ancient population of Transjordan. The Zamzummim are often identified with the people called Zuzim, mentioned as one of the nations defeated by Chedorlaomer and his allies in Transjordan.
Zamzummim" (used by the Ammonites) comes from the Hebrew, which literally translates into "Buzzers", or "the people whose speech sounds like buzzing." In Arabic the word zamzamah translates as a distant, unclear sound. They are described as having originally been a powerful and numerous nation of giants — "great, many, and tall".