Here's an easy venison tenderloin recipe I really like. It's pretty easy, but does need to be started at least a few hours, if not a day before you plan to grill.
To make this you'll need a tenderloin no less than 12 inches in length. If you'll be feeding a lot of people use a longer piece of tenderloin, and if needed use the whole thing as long as you can fit it both on your grill, and in your refrigerator.
Start by laying the loin on a piece of plastic wrap long enough to completely wrap and seal the loin. Smear the entire loin with a quality olive oil, being sure to get the ends and the underside.
Mince several shallots, and strip and chop several twigs of fresh thyme. Coat the entire loin with the shallots and thyme, then seal the loin in the plastic wrap and put in the refrigerator. The shallots and thyme should be pretty densely smeared on the loin, as some will fall off during grilling. Ideally, the loin should sit overnight, but at least let it sit for a few hours.
Next, prepare your grill. For this recipe, and most red meats you'll want your grill hot. The idea is to seal in all the delicious juices. When the grill is hot start grilling the loin. The olive oil may have gotten cloudy if the loin had been refrigerated long enough. Don't worry about that, it'll turn back into oil on the grill. As the loin cooks, turn it so you get every side.
How long you cook the loin is a matter of preference. I like my meat rare to medium rare, so after I've seared all the sides I don't leave it on too long. I'll not tell you how long to cook it, but please take care not to over cook, and dry it out. Venison is a rather sensitive meat, and can over cook easily. The best way to know when to take it off is to become familiar with the way meat feels as it's cooking. the more it cooks, the less it wiggles when touched.
After you remove the loin from the grill you want to let it rest for 10 minutes before you cut into it. This will allow the meat to retain it's juices. Because of the rest period it is probably best to take the meat off the grill a little before it has reached your desired done-ness, as the heat it retains will continue to cook it slightly.
When you are ready to carve, cut the loin into medallions, and dig in. If done correctly the loin should have some redness in the middle of each medallion you cut. How much is up to you, and depends on your cooking time.
I've used this recipe with great success to introduce people to venison. It also works well with beef, and probably any red meat. I hope you enjoy it.