Hrogn fra Osis is one of the larger fighting households in Ealdormere. It means 'The Spawn of Osis' in Icelandic. House Hrogn has produced many kings and queens who have reigned in at least three kingdoms: Ealdormere, the Middle Kingdom and Drachenwald.

House Hrogn was formed by Duke Sir Thorbjorn Osis Brandsson and his lady Duchess Caitlin Stuart (O.L.).

Although not all those who are descended from Duke Osis are members of Hrogn fra Osis, many are. Osis' lineage can be found at the Line of Osis.