Now in its 21st season, NBC's Law & Order: SVU has passed several significant milestones. It's now the longest-running primetime series on television and Olivia Benson played by Mariska Hargitay) has been there for the show's entire run. Beginning her career as a detective with the Manhattan Special Victims Unit branch of the NYPD, she has been the heart, soul, and now the face of the franchise for two decades.

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Since SVU first premiered in 1999, Benson has been not only an indefatigable force in the NYPD but for change in regards to the way the public views sexual assault. From her early days on the beat with Detective Elliot Stabler to her recent time as captain commanding a dedicated precinct of new detectives, she has proven time and again that SVU will be a rating superstar as long as she's leading. Here are 10 facts you didn't know about Olivia Benson. Dun Dun!

SHE'S SO BELIEVABLE BECAUSE OF MARISKA HARGITAY'S TRAINING

Mariska Hargitay's commitment to portraying Olivia Benson as accurately as possible resulted in her doing extensive research into sexual assault and its effects. She rode along in ambulances and conducted interviews with survivors, which not only informed her performance but inspired her to create the Joyful Heart Foundation.

Preparing for her role as Detective Benson opened her eyes to the staggering statistics of assault, abuse, and domestic violence inflicted on men, women, and children all around the United States. Through her foundation and with her role in SVU, she hopes to change the way the public views sexual assault through education and advocacy.

SHE'S THE FIRST FEMALE DETECTIVE IN LAW & ORDER HISTORY

Up until Olivia Benson came along, all other female leads were either district attorneys or psychiatrists. The detectives that investigated the crimes were traditionally men, until Law & Order: SVU decided that a female partner with Detective Elliot Stabler could make for gripping television.

They weren't wrong, because Olivia Benson could be as tough and gritty as Stabler but also empathetic and compassionate. She's known for being loyal to her partners, dedicated both to the NYPD and to survivors of trauma, and strong in the face of violent perps and sexism in the workplace.

Olivia's Conception

It was only later that Olivia tracked down the particulars of her mother's case and discovered her father had committed suicide. Her mother, a raging alcoholic, would eventually die from a fall in 2000.

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Benson could have let her trauma define her, but instead, she used it to make herself a stronger and more empowered advocate for survivors like herself.

HER CLOTHES & JEWELRY ARE FOR SALE

If you watch SVU closely, you'll often see Olivia Benson wearing various types of delicate jewelry. Her preferred hues tend to be gold, and she's known for layering necklaces that have different designs on them for a little bit of personal flair amidst her professional attire.

Many of the pieces she wears are available for purchase, along with certain pieces of her wardrobe, through the Joyful Heart Foundation. Proceeds from purchases go towards helping the survivors of sexual assault, and the catalog rotates depending on what she's wearing in a given particular season. It's a great way to give to a good cause and have a great SVU prop!

Olivia's CHARACTER WAS NAMED AFTER THE PRODUCER'S DAUGHTER

Both Olivia Benson and Elliot Stabler (her longtime partner) were named after producer Dick Wolf's children. Other references include a daughter in Rey (Benjamin Bratt's) family also named Olivia, as well as the inclusion of the character of Dr. Olivet.

Dick Wolf produced five series under the Law & Order brand, with Law & Order: Special Victim's Unit surpassing his original series Law & Order, which ended it's run in 2010 after twenty years on the air. It's now the only Law & Order series currently producing new episodes.

SHE KEEPS A PHOTO OF HER FAMOUS MOTHER ON HER DESK

If you've ever found yourself wondering why it is that Olivia Benson has a photograph of Jayne Mansfield on her work desk, that's because she is the mother of Mariska Hargitay. While Olivia Benson may not have a famous mother, Mariska comes from Hollywood royalty.

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She's the daughter of blonde bombshell Jayne Mansfield and bodybuilder Mickey Hargitay. He was a Hungarian-American actor who notably won Mr. Universe in 1955. Jayne Mansfield tragically died in an auto accident when Mariska was only three years old and asleep in the back of the car.

SHE'S ONLY MISSED 9 EPISODES THE ENTIRE SERIES

Law & Order: Special Victims Unit is the longest-running series in the Law & Order franchise by a long shot. In its 21 seasons, cast members have come and go, but none of them have put in the hours of work that Mariska Hargitay has.

It's no wonder that Olivia Benson has become the "face" of the series, considering she's only ever been absent from nine episodes out of 480. Her longtime partner Detective Elliot Stabler (Christopher Meloni) left the series during Season 13 (to much fan disappointment), but she remained a further 8 seasons and shows no signs of retiring.

Olivia Is the Longest-Running Drama Character On PRIMETIME TV

Since Law & Order: SVU is now in its 21st season, Olivia Benson will have been portrayed by Mariska Hargitay for a longer period of time than James Arness portrayed Marshall Matt Dillon in Gunsmoke (his record was 20), or Kelsey Grammer played Dr. Frasier Crane (20 between Cheers and Frasier). 

Playing Olivia Benson for 21 consecutive seasons seems like an entire lifetime. Mariska Hargitay hasn't appeared in very much else, unlike her castmate Christopher Meloni who starred in Oz while he was filming SVU. By playing Olivia Benson as she rose through the ranks from detective to sergeant, Hargitay's film career has mirrored Benson's career, which is undoubtedly a surreal experience.

Mariska Speaks MULTIPLE LANGUAGES

Olivia interrogates a suspect in SVU

When it comes to preparing for her role as Olivia Benson, Hargitay takes her research seriously. But one area where earlier studies came in surprisingly handy involved speaking to perps or victims in a foreign language. Hargitay had no problem there, being fluent in five languages herself.

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Hargitay is fluent in Hungarian, Spanish, French and Italian. Her mother, Jayne Mansfield, had an astounding IQ, so it's not surprising she's such a linguist. Peter Hermann, her husband (and defense attorney Trevor Langan on the show) speaks German, so no doubt that will come in handy during future interrogations.

Olivia Is A Survivor

Olivia Benson has her own struggles and inner demons, primarily involving her own brush with sexual assault. Her compassion for survivors of that sort of trauma comes from her brutal experience with it.

When William Lewis calculated a lethal attack against her in Season 15, which led to Benson being taken as a hostage and almost dying, fans thought they'd seen Benson at her lowest. However, she emerged a phoenix from the ashes, faced him in court, and moved on with her life in various positive ways, like moving in with her boyfriend, pursuing promotions within the NYPD, and adopting Noah.

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