Jedi Master Yoda was a puppet utilizing skills of Frank Oz (Collaborator with Muppet Master Hensen)

Despite being a three foot green alien puppet, Jedi Master Yoda manages to give off a convincing
impression of wisdom and deliver some of the "Star Wars" saga's most crucial lines. George Lucas
drafted in legendary Jim Henson-collaborator Frank Oz to bring the elderly Jedi to life, a choice
which ensured Yoda had a sense of humor to match his worldly knowledge.

Source: CNN