Lydia is a redhaired pig, who wears glasses and a magenta bikini. As suggested by her name, her body is completely covered in tattoos.
She was introduced in Episode 102: Connie Stevens when Kermit sang the song "Lydia the Tattooed Lady" as the opening number. Closeups revealed that many of her tattoos in fact correspond to those in the song, including the Washington Crossing the Delaware and the Battle of Waterloo. They were drawn by Jim Henson.
Unlike the other pigs on The Muppet Show, Lydia had hooves instead of hands.