Comedian Horatio Sanz allegedly groomed and sexually assaulted an underage superfan at a "Saturday Night Live" party — as cast members looked the other way, the woman claims in a lawsuit filed Thursday.

The unnamed Pennsylvania teen, who was 17 at the time, was running an "SNL" fan site in May 2002 when Sanz allegedly took her on a limo ride then "digitally penetrated her genitals" at a post-show bash, according to the lawsuit, filed in Manhattan Supreme Court.

The girl first met Sanz at age 15 — when he was 31 years old — in 2000 after he invited her to a taping of the sketch comedy show, according to the lawsuit, which names the actor and SNL Studios as defendants.

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The next year, he summoned her to several after-show parties where he allowed her to drink, touched her inappropriately and told her "to sit on his lap," according to the lawsuit.

In August 2001, when the girl was 16, Sanz allegedly contacted her via the instant message handle "Marblechomper," offered her tickets to the show and leaked her info about "SNL" hosts and musical guests, the suit states.

He then asked her to send him photos of herself and "to perform sexual acts, including masturbation, which he asked her to describe to him" — kicking off what would allegedly be a years-long cyber sex relationship with the teen, according to the lawsuit.

"Sanz exchanged messages with [the teen] and steered conversations to discuss sex, sexual experiences, sexual activities, sexual fantasies, masturbation," the lawsuit states, which notes he called her disparaging terms such as "slut," "slutty" and "bitch."

"Sanz exchanged messages with [the teen] and steered conversations to discuss sex, sexual experiences, sexual activities, sexual fantasies, masturbation."

— Quote from lawsuit
Horatio Sanz, SNL, Disney+, The Mandalorian, Los Angeles

Horatio Sanz is seen in Los Angeles, Nov. 13, 2019. (Getty Images)

According to the lawsuit, Sanz later "admitted and bragged to [her] that he masturbated during these conversations."

In September 2001, Sanz allegedly invited her to an "SNL" party where she drank beer with hard-partying former "SNL" actor Jimmy Fallon, Sanz and other NBC bigs, according to the lawsuit, which doesn’t name Fallon as a defendant.

"Plaintiff sat with Jimmy Fallon and others in a VIP area, ordered and consumed a Budweiser beer in the presence of NBC/SNL employees," the suit states.

"Plaintiff sat with Jimmy Fallon and others in a VIP area, ordered and consumed a Budweiser beer in the presence of NBC/SNL employees." 

— Quote from lawsuit
"Tonight Show" star Jimmy Fallon is mentioned by name in a lawsuit against former "Saturday Night Live" cast member Horatio Sanz. But Fallon is not named as a defendant.

"Tonight Show" star Jimmy Fallon is mentioned by name in a lawsuit against former "Saturday Night Live" cast member Horatio Sanz. But Fallon is not named as a defendant.

During the drug-fueled 2002 party where Sanz allegedly sexually assaulted the teen, he also fondled her in front of other party-goers at the star-studded bash, according to the suit.

His creepy actions included "kissing her, groping her breasts, groping her buttocks, and digitally penetrating her genitals forcibly and without [her] consent," according to the lawsuit.

One stunned party-goer responded, "Are you f—ing serious?" — but apparently did nothing to stop it, the suit alleged.

For the rest of high school, the teen became depressed, "regularly self-medicated with dissociative drugs" and was later hospitalized, according to the suit.

When she ran into Sanz at a comedy event in 2019, he apologized, said he "felt terrible" and admitted she could "#metoo" him for his actions, according to the lawsuit.

"[I] swear on a stack of improv books … I’m a different person," he allegedly said.

"I had a real issue with sex. I was stunted. I didn’t know how it worked," he added, according to the lawsuit. "I spent all my 20’s trying to be funny. So I wasn’t normal with girls."

"I had a real issue with sex. I was stunted. I didn’t know how it worked. I spent all my 20’s trying to be funny. So I wasn’t normal with girls."

— Alleged Horatio Sanz quote in lawsuit

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The woman is now seeking unspecified damages, according to the suit, which notes she’s a "victim of child sexual abuse" who suffered "psychological and emotional harm."

A spokesman for Sanz called the claims "categorically false" and said she’s simply out for money.

"However often she repeats her ludicrous allegations or tries to rope in other high-profile names to generate media attention, they will always be false," the rep, Andrew Brettler, said. "Before filing this lawsuit anonymously, she demanded $7.5 million in exchange for her silence. We, of course, refused and will vigorously contest these totally meritless claims."

Reps for NBC declined to comment Thursday. Fallon’s rep did not immediately return a request for comment.