Semar is a character in Javanese mythology who frequently appears in wayang shadow plays. He is one of the punokawan (clowns), but is in fact divine and very wise. He is the dhanyang (guardian spirit) of Java, and is regarded by some as the most sacred figure of the kotak (wayang set). He is said to be the god Sang Hyang Ismaya in human form.
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").
In depictions, Semar appears with a flat nose, a protruding lower jaw, a tired eye, and bulging rear, belly, and chest. He wears a checkered hipcloth, symbolizing sacredness. Like the other panakawan, the wayang kulit puppet does not have the elaborate openwork and ornamentation characteristic of the heroes In wayang wong, Semar always leans forward, one hand palm up on his back and the other extended partly forward, moving up and down, with an extended forefinger.
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 Sarahita (or Sarawita), who is the servant-clown of a demonic hero.

en.wikipedia.org/wiki/Semar