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- Andrew Nivens, aka "The Old Man" – The Puppet Masters (his name is not mentioned, only inferred – the President calls him Andrew and his son's last name is Nivens)
- Elihu Nivens, aka Sam Cavanaugh – The Puppet Masters
- Gwen Novak – The Cat Who Walks Through Walls
- Dr. Sven Nelson – Stranger in a Strange Land
Read more about this topic: List Of Robert A. Heinlein Characters