|Voice Actor||Charlie Adler|
|First Appearance||"No Smoking"|
|Last Appearance||"The Ballad of Cow and Chicken"|
Cow is Chicken's 9 year old little sister, with a weight stated as 600 pounds. Cow looks up to her brother Chicken, whom she lovingly refers to as "Big Brother", but she is often viewed by Chicken as infantile and stupid, and is quickly prone to emotional outbursts. She is the only character to appear in every episode of the the series.
Cow has employed Blackmail to get Chicken to do what she wants and often attempts to get the other characters to do the right thing. She also enjoys drinking her own milk and holding her utter. Cow's alter ego is "Supercow", a superhero with the ability to fly. Supercow's powers lie in a green blanket that she wears as a cape and her outfit is purple with a logo on the chest which resembles that of Superman. Her alter ego Supercow speaks Spanish, and often exclaims: "¡Supercow al rescate!" ("Supercow to the rescue!") (in the Spanish edition of the show, she speaks the catch phrase in English). Cow first became Supercow in the Pilot, "No Smoking."