Cesar Millan's television show Dog Whisperer on National Geographic debuted in 2004, but Millan previously spent years struggling to pursue a career as a dog trainer.
Robin Layton/Courtesy of Cesar Millan
Neil deGrasse Tyson is hosting Cosmos, the science documentary series made popular by Carl Sagan. Tyson is Sagan's successor as America's most famous scientist.
Richard Shotwell/Richard Shotwell/Invision/AP