Parmeniscus was a Pythagorean philosopher who lived during the 2nd century BCE. Very little is known about his life. He is mentioned only once in surviving ancient literature, by the later philosopher Iamblichus, who lists him as an author who wrote about the Pythagorean "symbols."

These symbols were a collection of cryptic rules and sayings, like "do not step over a yoke," that defined the Pythagorean way of life. Parmeniscus's work, titled On the Pythagorean Symbols, was a collection or commentary attempting to explain their meaning. The book itself has not survived; we know of it only through Iamblichus's reference.

His historical importance is as a minor link in the long tradition of Pythagorean thought. According to modern scholars, figures like Parmeniscus worked to preserve and interpret the school's teachings long after its founder's death. His lost writing represents the kind of scholarly activity that kept Pythagorean ideas alive, eventually influencing later philosophers like the Neoplatonists who sought to revive these ancient doctrines.