The Ny Carlsberg Glyptothek is a museum primarily devoted to sculpture founded by a member of the Carlsberg beer dynasty. It has quite a comprehensive collection of Roman portrait busts. Here are a few of the more interesting ones.
First, here's a rare surviving bust of Caligula with a reconstruction of its original coloring:
I wonder if the resemblance to Joffrey Baratheon, the young psychopathic king on Game of Thrones, is accidental:
And now to hands-down the least flattering portrait bust of a Roman Emperor you will ever see:
Behold Vitellius, the Homer Simpson of Roman Emperors. Fat, profligate and cruel, Vitellius was one of the ill-fated lot who ruled for a few months in AD 69, the 'Year of the Four Emperors.' Suetonius describes him as '[s]tained by every sort of baseness' and notes his other charms: 'He delighted in inflicting death and torture on anyone whatsoever and for any cause whatever.'
Finally, here's a bust that's probably of Cato the Younger:
Now that's the face of pained patrician integrity. It's also the face of Christopher Walken: