Born in 1927 in Agrinio, he studied at the drama schools of Sokratis Karatinos and the National Theater and participated in several classic films of Greek cinema such as Thiasos and The Stone Years. Grammenos became widely known from the role of the servant Mathios of the film family of the "Fourtunakis" in the film "The Fairy and the Boy". He was one of the co-founders of the cooperative troupe of S.E.H. Arma Theater, while he also worked as an assistant director in the cinema. He worked as a journalist in the literary magazine Efitheorisi Technis, where he wrote theater and cinema reviews and in 1974 he founded the publishing company Thymari.

Ο Θάνος Γραμμένος είναι Έλληνας ηθοποιός.