In 'Interstellar', the planet closest to the black hole Gargantua is Miller's planet.
Named after the astronaut Laura Miller, the planet is the first world visited by the Endurance crew after passing through the wormhole near Saturn. It lies extremely deep in Gargantua's gravitational field, producing the film's famous time-dilation effect: roughly one hour on the planet corresponds to about seven years for observers far from the black hole.
Miller's planet appears to be covered by a shallow global ocean, but enormous waves make the surface catastrophically dangerous. The crew initially mistakes the planet's conditions for evidence of habitability, only to discover that Miller's mission ended almost immediately after landing. The other candidate worlds are Mann's planet and Edmunds's planet. Mann's world is farther from Gargantua and frozen, while Edmunds's planet is ultimately presented as the most promising destination. “Miller” refers to the astronaut and the planet named after her, not to Cooper or another crew member.