A fictional spaceship created by Robert A. Heinlein.
The New Frontiers, along with its sister-ship the Valiant, was a huge multi-generational ship designed for interstellar travel. During the persecution of the Howard Families which followed the end of the Masquerade, the ship was commandeered by Lazarus Long to take the exiled Howards away from Terra.
The commandeering of the New Frontiers by Lazarus Long takes place in the novel Methuselah's Children.