There was an Irishwoman named Delia Bridget McDermott who survived the Titanic
disaster. There are some quite fanciful stories about her, starting with a supposed encounter with a "little man" just before she left her native Ireland for the voyage. Reportedly, this "little man" (probably a Leprechaun
) told Delia that she was going on a long voyage on which there would be a disaster but that she would be saved.
Delia McDermott boarded the Titanic
at Queenstown as a Third Class passenger with several other Irish people. A further story is that she had bought an expensive hat the day before and was very proud of it. She was asleep during the collision but was at some stage hustled into a lifeboat. Then she reportedly realised that she had forgotten her precious hat, jumped back onto the sinking ship, went to her cabin to get her hat and so missed that boat. She eventually survived on Lifeboat #13.
Looking at that fanciful story, Dylan McDermott comes across as rather too bland to be Delia's descendant.