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.

The Late Show legend David Letterman has slammed CBS’s “gutless” axing of his successor, Stephen Colbert, and the entire franchise.