David Letterman delivered a fiery rant against CBS and parent company Paramount for cancelling Stephen Colbert’s “Late Show,” calling the decision “gutless” and “pure cowardice” as he labeled his successor a martyr of the network.

While ratings for Colbert's show have declined over the last decade, the program has consistently achieved the highest views of any show in the 11:35 p.m. hour, outdrawing ABC's "Jimmy Kimmel Live" and NBC's "The Tonight Show Starring Jimmy Fallon," according to Nielsen.