Chicken Liver is a character from Sam and Friends, also known as Theodore. He is an abstract humanoid character with a tall head and a big nose.
According to Designs and Doodles, Chicken Liver "was a dramatic storyteller who believed that Sam and Friends lacked culture (Much like Sam the Eagle from The Muppet Show). He promised to enrich the show with classical literature, including such epic stories as The Three Little Pigs."
Jane Henson said at MuppetFest that Chicken Liver was one of her favorite characters. When Sam and Friends ended, she and Jim kept the puppet in their home, and it had to be significantly repaired before being donated to the Smithsonian Institution.