Tilly Gaunt's birth name is Matilda Gaunt.
His name was Gaunt!~To be more thorough... the grandfather of He-Who-Must-Not-Be-Named was Marvolo Gaunt
The House Of Gaunt
Tom Marvolo Riddle and Marvolo Gaunt are characters in a fictional story... you know what the word 'fiction' means, do you not?
Nope she died soon after the birth of her son. She lived long enough to name him Tom, after his father, Marvolo, after his grandfaher. Tom Marvolo Riddle later know as Lord Voldemort.
Merope (Gaunt) Riddle.
Genevieve Gaunt's birth name is Genevieve Wilhemina Gaunt.
Tilly Wedekind's birth name is Tilly Newes.
Tilly LaForge's birth name is Matilda Jane LaForge.
Tilly Losch's birth name is Ottilie Ethel Losch.
Tilly Lus's birth name is Mathilde G. Barbiers.
Meg Tilly's birth name is Margaret Elizabeth Chan.
Tilly Walker's birth name is Clarence William Walker.
Jennifer Tilly's birth name is Jennifer Elizabeth Chan.
Theresa Tilly's birth name is Theresa Mary Catherine Seyferth.
Jeanne Ravel's birth name is Jeanne Gaunt.
Gertrude Berg's birth name is Tilly Edelstein.
Ingrid Andree's birth name is Ingrid Tilly Unverhau.