The Do-Not is a minor character in Bunsen Is a Beast, who first appeared in "Beastern Standard Time". He is voiced by Carlos Alazraqui. He is a no-nonsense beast who warns against negative choices a person (or beast) is about to make, which he begins with "Do not..." each time he speaks. This annoyed Bunsen and Mikey, which they told him to go away, but Bunsen eventually agreed with him once over a donut he felt he shouldn't have because he and Mikey was tardy in school.
The Do-Not is primarily yellow, with shades of orange on his long nose and tail. On his belly is a orange no symbol and his eyes are also orange.