Helen Robichaud (first appeared in Everything's Eventual)

Helen (known as "Mama Sweet") is mentioned in the short story "The Man in the Black Suit." She's the oldest woman living in Motton, Maine and is the reason the narrator's mother stopped going to church.

Helen Robichaud is mentioned in the following books:

Under the Dome (Nov 2009)

Nora Robichaud is one of the victims of the dome - and perhaps a relative of Helen Robichaud?

On the road behind him, Nora Robichaud honked. Her best friend, Elsa Andrews, tutted. The two women, both retired nurses, exchanged a glance but not a single word. They had been friends too long for words to be necessary in such situations.
- Part 5 / Chapter 2

Revival (Nov 2014)

Pretty sure Duane is a relative of Helen's.

“Well, not him, exactly. Mom said he couldn’t because it’s too dangerous, but some guy. Maybe Duane Robichaud. He runs Brownie’s Store along with his mom and dad. He drove the nine-car at the Speedway last year, but the engine caught on fire. Dad says he’s looking for another ride.”
- Chapter I