It was he who brought Hollywood 10 screenwriter Dalton Trumbo out of the cold to write the screenplay for the Communist themed movie, "Spartacus", which in turn was based on a work by Marxist author Howard Fast. Thus he spat in the eye of the country which had rewarded him so handsomely.
The words “I AM SPARTACUS!” is strictly a Dalton Trumbo addition to Howard Fast’s novel. It, and the Tony Curtis character are not in the book.
I’ve read the book and find I prefer THE GLADIATORS by Arthur Koestler.