The beloved works of Nickelodeon animation dominated the 1990's; programs such as RugratsDoug, and Spongebob Squarepants were introduced to global audiences and individuals across the world became enamored with these aptly named "Nicktoons." A featured gem in their animation crown was Hey Arnold!, a show that followed the adventures of 4th grader Arnold, while simultaneously exploring the interpersonal connections he formed with his family, friends, and neighbors.

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Running from 1996 until 2004 and spawning two films, Hey Arnold! was a cultural juggernaut that left an impression upon the world that is still felt to this day. Across its eight-year run, numerous characters would flit in and out of Arnold's life, and in the real world they were voiced by a vast cast of actors, including some surprising stars. Diving into the pool of 90's nostalgia, here are 10 celebrity voice actors you had no idea starred on Hey Arnold!.

Tim Curry

Tim Curry has been dazzling audiences for decades, starring in films ranging from Muppet Treasure Island to The Rocky Horror Picture ShowPerhaps best known to animation fans as Nigel in The Wild Thornberrys, voicing the eccentric filmmaker was not his first time working with Nickelodeon.

On Hey Arnold!, Curry provides the voice for Mr. Leichliter, a director and theatre critic. On the show, Curry provided his voice on three separate episodes, culminating with Leichliter staging a full-scale musical starring Arnold and his classmates, entitled "Eugene, Eugene!."

Lacey Chabert

Instantly recognizable as Gretchen in the perennial classic Mean GirlsLacey Chabert also made two guest appearances as Ruth P. McDougal, the object of Arnolds' affection, throughout the first season of the show.

While Ruth is featured in season one and frequently mentioned, Arnold relinquishes his crush following the realization that she isn't actually the girl of his dreams; after this, she is regulated to background appearances. In her most prominent episodes however, Chabert brings Ruth to life, years before the actress would make Gretchen Wieners a household name.

Kathie Lee Gifford

TV personality and author, Kathie Lee Gifford, provided a cameo appearance on the show in the 1999 episode, "It Girl." In the episode, Gifford voices Jackie Lee, a talk show host and parody of her real-life persona.

While only provided a short appearance on Hey Arnold!, Gifford has provided voice work for numerous other animated series throughout her career, including The Simpsons and Hercules.

Ryan Seacrest

Ryan Seacrest hosting American Idol, holding a mic

Years before he became a cultural icon, Ryan Seacrest entertained animation audiences in his one-off appearance on Hey Arnold!. In the episode "Fighting Families," Arnold and his chosen tribe of neighbors compete on a game show comprised of physical and mental challenges against a rival familial clan.

Seacrest provides the voice for the host of the show, allowing himself to gain experience moderating a fictional show before he'd dominate the new millennium as the host of American Idol

Jamie Farr

In the 1997 episode "The High Life," Arnold's best friend Gerald gets roped into a pyramid scheme by wristwatch distributor, Mr. Wacko. Gerald is provided a large sum of Wacko Watches, but after peddling to everyone he knows, he is left with a surplus of the devices and no one to sell them to.

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In the end, Wacko buys back the watches from Gerald, who in turn provides him with a new slogan, "Only a wacko doesn't own a Wacko." Mr. Wacko himself is brought to life by Jamie Farr, of M*A*S*H fame, in Farr's first voiceover role since the 1970's and, as of 2020, his most recent.

Jennifer Tilly

Jennifer Tilly has a career that spans decades, with appearances in films such as Liar, Liar, The Haunted Mansion, and Bride of Chucky. In the 90's, Tilly made a guest appearance on the episode "Ernie in Love," where she portrays plus-sized supermodel, Lola. Viewers watched as Ernie, a neighbor of Arnolds', falls in love with her after seeing an ad she was featured in, and then attempts to woo the fabulous fashionista.

Following a first date, Ernie asks her out for another, to which she initially refuses due to the optics of her dating someone so much shorter than she is. Ernie returns home, heartbroken, but the next day Lola visits to apologize and the two agree to meet for coffee, hinting at a burgeoning relationship, though she is never seen in the series again.

George Takei

Star Trek star George Takei is an international icon, a Broadway star, and from 1997 until 2004 he voiced the character Kyo Heyerdahl on Hey Arnold!. Kyo is the father of Phoebe, an Asian-American classmate of Arnolds at their school, P.S. 118. While not a major character, Takei is notable for providing his celebrity status to more than one episode, unlike many stars who were simply brought in as single appearance characters.

Also noteworthy is the casting of Takei to play a character of Asian decent; it would have been easy for production to pull from their stable of regular voice actors for the role, but utilizing Takei was a commendable choice in representation for the casting department.

Julia Louis-Dreyfus

Saturday Night Live alum and Seinfeld actor, Julia Louis-Dreyfus, gifted her talents to Hey Arnold! in the 1997 episode, "Crush on Teacher." Louis-Dreyfus plays Miss Felter, a substitute teacher who Arnold becomes infatuated with and, through a series of miscommunications, accompanies her on a "date."

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Eventually it is revealed that her fiancé also shares the name Arnold, which was the central reason for the misunderstanding between the two. After the mix-up is revealed, Arnold leaves dejected, but optimistic about his future, and Miss Felter is never heard from again, although she does make background appearances for the rest of the shows run.

Phyllis Diller

Actress and comedy legend, Phyllis Diller, lent her vocal stylings to character Mitzi Shortman, in the 1999 episode, "Grandpa's Sister." In the show, Arnold is tasked with repairing a decades-long rift between the Grandpa and Mitzi, which was forged following the loss of their childhood dog.

Diller, whose entertainment career began in the 1950's, was no stranger to voiceover work, where her credits include A Bugs Life, The Adventures of Jimmy Neutron, and Family GuyUnfortunately, the world lost Diller in 2012 following years of medical complications, though her legacy of comedy will forever be immortalized.

Mark Hamill

Mark Hamill has a voiceover resume almost as bountiful as his live-action one. Though best known as Luke Skywalker, Hamil has also provided his vocal skills to numerous animated roles, including the Joker in various Batman-related media. Wish such an illustrious career, it's easy to overlook his lesser-known roles, including his appearance on Hey Arnold!. Grubby, voiced by Hamill, is a character in the show, often shown in the background and is presumed to be homeless, based off his appearance and apparent lack of employment.

In the episode "Das Subway," Arnold and his friends get trapped in a subway car with an eclectic mix of other characters, including Grubby. As the mood in the train car worsens, it is Grubby who begins to sing a song of friendship, which helps alleviate the tension in the claustrophobic train car.

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