The woman in this picture probably doesn’t look familiar to you, but it’s likely that you know something about her.

Christine Fox is the former Maritime Air Superiority specialist who inspired Charlie, the Top Gun instructor who took off with Maverick’s heart in the 1986 movie named after the Navy Fighter Weapons School.

She’s also the Defense Department’s acting deputy defense secretary, as of Dec. 3, a position she’ll hold while the Pentagon searches for a permanent replacement for outgoing Deputy Defense Secretary Ash Carter.

Fox never actually taught at Top Gun, but she used her math and physics background to develop tactics for aircraft carrier defense at the Center for Naval Analyses, across the street at Naval (now Marine Corps) Air Station Miramar in San Diego.

According to a 1985 People magazine article, Top Gun’s producers originally planned to introduce a gymnast or groupie as Lt. Pete Mitchell’s love interest.

But then, during a meeting on base to discuss filming, the air wing’s commanding admiral asked Fox, then 30, to step into his office for a moment. And as the legend goes, Charlie was born.

Fox never drove off into the sunset on the back of a fighter pilot’s motorcycle, though. Unmarried at the time, the People article said, she had never been involved with an aviator.

Capt. Monroe “Hawk” Smith, the wing’s former operations officer, called her a “straight arrow.” He’s the one who came up with her honorary call sign: “Legs.”

Cmdr. Harry Hunter told People at the time, there was no problem taking her seriously.

“She’s so professional that her looks don’t become a point of interest,” Hunter said. “When she walks in you say ‘wow,’ but 30 seconds later you’re talking business.”

She had a similar view of the situation.

“The fact that I know so much about what these guys are doing every day and they come in and talk to me about it—why is my radar doing this?—changes the relationship,” she said. “It takes some of the romance out.”

Fox moved back to CNA headquarters in Alexandria, Va., before the movie came out, moving up the ladder and eventually becoming the group’s president.

She also served as the scientific analyst to the chief of naval operations, according to her Pentagon bio.

She later worked as the director of the Defense Department’s Cost Assessment and Program Evaluation, but left the Pentagon in June to become senior adviser to the Johns Hopkins Applied Physics Laboratory.

She stayed on as an unpaid consultant to Carter, keeping her updated on Pentagon affairs.

While Fox will “have all rights and responsibilities that the deputy secretary of defense would have,” she will not be in the line of succession, a senior defense official said this week. Army Secretary John McHugh, the senior most service secretary, is first in line.

Carter called Fox “remarkably brilliant” during his Monday farewell ceremony at the Pentagon.

It’s unknown whether anyone still uses her call sign, but according to People magazine, the guys at Top Gun came up with a new nickname after the movie went into production: Star.