The Star Beast is a 1954 science fiction novel by Robert A. Heinlein about a high school senior who discovers that his extraterrestrial pet is more than it appears to be. The novel was originally serialised, somewhat abridged (as Star Lummox), in The Magazine of Fantasy & Science Fiction (May, June, July 1954) as Star Lummox and then published in hardcover as part of Scribner's series of Heinlein juveniles.
Not the usual science fiction, this deals more with diplomacy and politics. Good character interactions and manipulations make this a very enjoyable read.
