Elsam, Elsie, Ilslie
The Duchess of Brabant who married Loherangrin (Lohengrin), Perceval’s son, after he saved her from a forced marriage to her steward, Friedrich of Dundramunt (Frederick de Telramund).
Loherangrin made her promise never to ask his name or lineage, but she was coerced to do so by the Countess of Kleve. In response, Loherangrin left her and returned to his own kingdom, though Elsam had borne him two children.
In the German Lorengel, Loherangrin does not leave and they live happily ever after.
Sources
Lohengrin | c. 1283-1289
Lorengel | 15th century