The Queen of Halloweentown is the un-named wife of Marvin and the mother of Splendora Agatha Cromwell. Like her husband she is never seen in the films and unlike her husband she is never mentioned. The Queen is referred to as the Queen of Halloweentown because her daughter was the next Queen in Halloweentown, so naturally Aggie's mother would be the former Queen. It's said that Dylan was the first warlock in the Cromwell family. This could mean that the family name Cromwell is a matriarchal name which is also supported by the fact that throughout the films multiple characters pronounce that the Cromwell family are very powerful witches. As would be the case it means that the Cromwell family (with the exception of Gwen) kept their maiden names to pass down. Another theory is that the Queen took the name Cromwell from her husband and started the Cromwell line of witches. The most common point of debate for this theory is that if Agatha was the only Cromwell Witch living in Halloweentown why would citizens proclaim multiple witches.