He is portrayed by Vin Diesel.
Riddick has been described frequently as a psychopath. He has never shown any remorse for the murders he commits nor does he show much empathy for those around him. However, Riddick may more accurately be called an animal, as his crimes originate from his ruthless will to survive rather than for the sake of killing. He has even referred to himself as an animal at times. Due to feeling the rage of his kind for as long as he can remember, Riddick's mental state has been regularly pushed to its limits.
Despite this however Riddick's personality most reflects a true survivor. He will do whatever he must to survive and will kill anyone who tries to end him or his freedom. At the same time, he is not without some form of morality. He is not one to kill those he does not view as a threat to himself. Likewise, if someone gets close enough to him they become part of the "Kill All Who Threaten" mindset, willing to defend them. Noticeably, Riddick also has a sympathy for children, as he was willing to risk his life to save Kyra.
Riddick has a low opinion of himself, despite valuing his continued existence. This conflicts with his destiny to avenge his race. When Fry died trying to save him, Riddick could only scream "Not for me!" believing his life was unworthy of her sacrifice. He also expresses deep regret and sadness when Kyra sacrifices herself for him.
In The Chronicles of Riddick, he considered it an insult, when he discovered the bounty placed on him was around a million of the currency for most planets, and when Toombs has a small crew to capture him (it was originally four crew members, then it was five).
Riddick personality falls under the alignment of Chaotic Neutral.