“The first known appearance of Semar and his sons is during the Majapahit era. In 1358 in relief of Sudamala in Candi TIgamangi, and in Candi Sukuh dated 1439. The relief was copied from a wayang story from the period, where Semar was first known to appear.

As Semar is one of the few characters in wayang stories not from Indian mythology, his origin is obscure. One hypothesis is that he and his sons are old indigenous deities who became cursed and demoted to servants with the importation of the kshatriya heroes of the Indian epics. Semar also resembles the vidusaka clown figure of Indian Sanskrit drama. The name Semar is said to derive from the Javanese word samar ("dim, obscure, mysterious"). He is often referred to with the honorific, "Kyai Lurah Semar" ("the venerable chief").

Semar and his sons first appear in the second part of the plays (pathet sanga), as the servants and counselors of whoever the hero of the wayang play is. In wayang plots, Semar is never mistaken and is deceptively powerful. He is the only character who dares to protest to the gods, including Batara Guru (Shiva) and Batari Durga, and even compel them to act or desist.

He often represents the realistic view of the world in contrast to the idealistic. His role as a servant is to cheer up those in despair and blunt the pride of the triumphant.

By tradition Semar has three sons, the other punakawans in the wayang: Gareng, Petruk, and Bagong (Bagong does not appear in Surakarta-style wayang). In some wayangs, he has a brother Togog (or Hyang Antaga), who is the servant-clown of a demonic hero. “

Semar - Wikipedia