Joshua Sasse gets naked 11 minutes in episode 3 of season 1. We first see his tatooed butt.
Then 12 minutes in the episode, we briefly see his thick uncut penis.

33 minutes in the movie, there is a long scene showing Jean-Claude Van Damme completely naked. The camera does not however show any frontal nudity, but we get ample view of his butt.

Paul McGann is naked first 84 minutes in the movie. He is naked in a bedroom. We see him from the back, so only his butt.
Then 100 minutes in the movie, Paul McGann is running naked in a forest. We see his butt and also his dick and balls moving around as he is running.

12 minutes in the movie, Bug Hall is running naked in a forest. We get a quick view at his big cut dick.
13 minutes in the movie, he gets stopped by the people chasing him and we get a view at his butt.

Fifteen minutes in the movie, after an intense tension between James Duval and Johnathon Schaech, we see James Duval getting naked in the bathroom. We see his butt and his ball at length. James Duval has a very nice hairy crack and butt. Johnathon Schaech watches James Duval make love in the tub, and jerks himself off to completion. We only see the result on his hand, that he eats up! Towards the end of the movie, Dewey Weber is completely naked, wearing nothing but a sock on his cock and balls.

In episode 8 of season 1, we get to see a lot of nudity. There is the much expected rear nudity of blonde cutie Jai Courtney. We see his butt as he is making love to a woman. We hope we will get to see front nudity from him someday. Episode 8 is also an episode where threee new slaves are brought in: Mike Edward, Daniel Feuerriegel and Ande Cunningham. We see rear nudity from the three of them as they need to be presented naked. They all three have nice butts. In addition to that, there is the much commented front nudity of Mike Edward. During that scene in the area where we see all three butts, we get to see Mike Edwards huge uncut dick. It's obviously a prosthetic. On the Blu-ray version of the show, there is an extra scene with front nudity of Mike Edward.

In episode 4 of season 1 of this HBO TV show, James Purefoy is seen completely naked in the middle of a courtyard and shows us a full frontal. While his naked body is cleaned by a male slave in front of everybody, James Purefoy shows us his big uncut dick. He is not moving much but the scene lasts long enough to be able to see it in great details.

Craig Parker appears fully naked in the season 3 of Spartacus. He proudly shows there his thick cut penis. His pubes are shaved.

35 minutes in the movie, we see Jason Behr's butt as he is making love to a woman. Jason Behr has an incredible lean body.

6 minutes in the movie,Thomas Jane is naked at the beach. We see his butt and also his rather small cut penis. Quite a disappointment for the star actor of TV show "Hung", who plays the role of a porn actor with an oversized penis. 22 minutes in the movie, Thomas Jane is singing and dancing naked. But the scene is dark and back-lit so we cannot see too well. However we do see the shape of his penis and balls bouncing around.