Sounds like what has been described to me as night terrors, which are distinguished from nightmares by whether or not the child actually is awake when you go to comfort them. If they respond to you coherently, it's a nightmare. If they don't it's a night terror. Night terrors, from what our pediatrician said, you just have to deal with; they just some annomaly you have to deal with until the child grows out of it.
However, if it's nightmares, there is a lot you can do. First, stop TV exposure within a couple hours of bedtime. I know I'll get a lot of flack for this, but it's true that it eliminates a lot of scary images for toddlers. My son generally only watches PBS shows or movies like Cars, but he was seeing this cold-medicine commercial where the guy is a monster and was having nightmares about it. That was when he was about 2.5 y.o. Now that he's 4, we have to be careful not to let him see Ursula the Sea Witch for long when he watches The Little Mermaid; invariably he'll have nightmares about her. To contrast, however, no problems with Monsters, Inc., which you would think would be automatically scarry. It's just different for every kid.
As an aside, if your son does not have a developmental reason to not be talking yet, get him going with sign language. Joseph G. has a great set of resources you can even get on Amazon.com to teach common words in sign. This allows toddlers to express themselves when they can't physically form the words with their mouths. Things like "drink" "eat" "play" "more" "all done", colors, foods, feelings, illness can all be learned within a VERY short period of time and may help you, as it did me, defer MANY temper tantrums over whether my son actually was done eating or not.
Good luck, and I'll pray for you to get a good night's sleep! :-)