Plenty of people go by a nickname, but they know it’s usually a derivation or diminutive of their given name. Not so actress Maggie Gyllenhaal, who recently —at the age of 36—discovered that her real name is Margalit.

Margalit is Hebrew for pearl, and it is used in Israel as both a first and a last name. For instance, singer Margalit Tzan’ani, journalist Dan Margalit, and politician and hi-tech entrepreneur Erel Margalit are familiar figures to those who follow Israeli culture and society.

Gyllenhaal, sister to actor Jake Gyllenhaal, swore up and down during a recent interview on ABC’s Live! with Kelly & Michael that she never knew her name was anything other than Maggie.

She discovered that her name was actually Margalit when she asked her parents to find her birth certificate so she could take care of bureaucratic requirements involved in her legally taking on the last name of her husband, actor Peter Sarsgaard.

Gyllenhaal, who currently stars in “The Honorable Woman,” a BBC and Sundance spy thriller miniseries about the Israeli-Palestinian conflict, recounted that it took her parents, screenwriter and producer Naomi Foner (who is Jewish) and director Stephen Gyllenhaal, a while to dig up the birth certificate.

When they did finally find it, it had “Margalit,” not “Maggie,” on it.

“I actually really love that. But it’s not my name,” the actress said.

“I grew up with Maggie on everything. It’s on my driver’s license, it’s on my passport, everything.”

Gyllenhaal said that her parents had not remembered that they had named her Margalit, and that her mother still insists that she officially dubbed her Maggie.

The actress joked that she is willing to cut her mother some slack. As a mother of two children herself, Gyllenhaal said she knows that overwhelmed new mothers can be forgetful.

“But my dad, maybe, should have known,” she said.

Gyllenhaal closed the conversation by saying that she truly likes “Margalit” and wished the Hebrew moniker were hers.

“Maggie’s my name,” she said.