There is a salad dressing that claims to contain 0 calories made by Walden farms, but it's basically a mass of chemicals and water, with some seasonings in there in such small amounts that the amount of calories is considered negligible and not counted per serving size.
If it has real food in it, then it will have real calories

Even so-called negative calorie foods contain calories and they don't really use more calories to digest than they contain. However, celery might be a good one to consider. It's very high in fiber, and low in calories, and it would be seriously difficult to consume many calories from celery
