Yes. When I go to a restaurant, it's nearly always on my own unless I'm attending a geocaching event or going to an after-gig meal.
Addendum: I read some of the other answers to this question. I don't think eating alone is any better or worse than eating with others. It's different and it is what it is. I can say that there are significant trade-offs for having company along. There's more planning to do, people might be too late or too early, and there's sometimes one person in the bunch who is being annoying and making a big issue of my food photography. Also, splitting the check can be tricky.