The late-night legend took aim at his former network home and David Ellison's media company, speculating that Colbert's show was canceled for political reasons.

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.

David Letterman took aim at his former employer, CBS, over the cancellation of 'The Late Show With Stephen Colbert.