The Lion (A Midsummer's Nightmare)

The Lion was a character in William Shakespeare's play A Midsummer Night's Dream.

While discussing the play, the Fourth Doctor suggested that he could play Thisbe and Romana II could play Pyramus, though wondered aloud if it was "the other way around". This left K9 Mark II with the part of the Lion. He gave a growl of displeasure at the idea, only for the Doctor to tell him that "lions don't growl, you know, they roar". The Doctor roared as an example and asked K9 to try it but he said nothing, instead turning away in disgust. (PROSE: A Midsummer's Nightmare)

Behind the scenes
Pyramus, Thisbe and the Lion actually originate from a tale in Ovid's and do not properly appear in A Midsummer Night's Dream. Instead, they are treated as fictional with other characters in the play portraying them and acting out the story.