The morning star was a medieval weapon resembling a mace, but with a large spike on the end and smaller spikes around the circumference. It was also known as the goedendag (from the Dutch word for "good day") and the holy water sprinkler (from its resemblance to the aspergillum sometimes used in the Catholic Mass).

It was used by both cavalry and infantry; the horseman's weapon typically had a shorter haft than the footman's, which might be up to six feet long. It came into use in the beginning of the 14th century.

The name "morning star" is often erroneously applied to the military flail (also known as the therscol), a similar weapon, but with the head attached by a short chain.