Deheubarth
The ruler of Deheubarth was King Hywel ab Edwin ab Einion, who had ruled since 1033 and would continue to do so until 1044.
England
The ruler of England at the beginning of 1042 was King Harthacnut, who had ruled since 1040. This year, King Eadweard III (Edward the Confessor) would take over.
Gwynedd
The ruler of Gwynedd was King Gruffydd ap Llywelyn, who had ruled since 1039 and would continue to do so until 1063.
Scotland
The ruler of Scotland was King Macbeth (The Red King), who had ruled since 1040 and would continue to do so until 1057.