Recurring Guest Characters Ric Ocasek 1 guest appearances Sam Waterston 1 guest appearances Shane Smith 1 guest appearances Steven Pinker 1 guest appearances Stone Phillips 1 guest appearances Thomas Friedman 1 guest appearances Tim Meadows 1 guest appearances Tom Brokaw 1 guest appearances Alex Trebek 1 guest appearances David Hallberg 1 guest appearances David Leonhardt 1 guest appearances Francis Collins 1 guest appearances George Lucas 1 guest appearances Jon Batiste 1 guest appearances Nicholas Kristof 1 guest appearances Samantha Power 1 guest appearances Yo-Yo Ma 1 guest appearances David Gregory 1 guest appearances George Takei 1 guest appearances Chuck Todd 1 guest appearances ⇤ « 1 2 3 4 5 6 7 » ⇥