Do hornets go dormant during winter?

It depends on what you mean by "hornet." There are many species of wasps called "hornets." Even those considered "true hornets" by scientists comprise more than 20 species.

Even the simplest answer has to be "yes and no." In temperate zones, most hornets die before winter. Only the fertilized queens live in a dormant state until the next spring, when the begin building a new colony.

In warmer areas, hornets can live year-round.

I've found white-faced hornets hibernating under rotten logs. There were about four or five of them together. Scientific sources suggest that only the queen should be hibernating alone, but I found a number of them hibernating together!