Mrs. Domzalski is an unseen character in Trollhunters.
When Toby was about two years old, Mrs. Domzalski and her husband, Ralph won the state lottery. They then went on a cruise, but there was a storm which they unfortunately got caught in. And were presumably killed at sea as Toby mentions that his parents never made it back.
Since then, Toby lives with Nancy and when good things happen he likes to think it's because of them.
- Within Nancy's house, there's a picture of a lady, that could either be her or Nancy herself as a young woman.