One Tree Hill aired on The WB for nine memorable seasons, spawning successful careers from its main cast, including lead actors Chad Michael Murray and Sophia Bush, Hallmark Channel star Bethany Joy Lenz and fan-favorite Hilarie Burton Morgan, who would later guest-star alongside her real-life husband, Jeffrey Dean Morgan, on The Walking Dead.

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Throw in Barbara Alyn Woods, known for her role in Chucky, and The Lion King's Nala herself, Moira Kelly, and OTH was full of megastars. But it was also full of some mega guest stars from the show's start to finish.

Pete Wentz As Himself

Pete Wentz on One Tree Hill

Pete Wentz of Fall Out Boy fame is no stranger to making cameos on popular TV shows, but his first-ever guest appearance was a three-episode arc on One Tree Hil season 3, where the rocker played himself.

Wentz, along with his fellow Fall Out Boy bandmates, perform at Tric, and after a brief romance with Peyton, later perform at her breast cancer benefit concert and agree to include a track on her charity album Friends With Benefit.

James Van Der Beek As Adam Reese

James van der Beek on One Tree Hill

A special guest star for four episodes in season 6, James Van Der Beek appeared as Adam Reese, a movie director who is enlisted to direct the adaption of Lucas' novel, An Unkindness of Ravens.

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Van Der Beek's character wasn't much help to Lucas in his endeavor to bring his novel to film, clashing with the author until the entire project was shut down, causing Adam to rejoice in getting paid for doing nothing while Lucas mourned the loss of his film adaption.

Nick Lachey As Himself

Nick Lachey on One Tree Hill

Like many musicians who guest-starred on One Tree Hill, Nick Lachey appeared in three episodes of season 6 as himself. In the show, Lachey is looking for a new song to record and arrives in Tree Hill with plans of buying the rights to one of Haley's songs.

Not only does Lachey record Haley's song "All In My Head" — which was written by Lenz — but he also winds up in a romantic relationship with Brooke during her time in Hollywood.

Torrey DeVitto As Nanny Carrie

Torrey DeVitto on One Tree Hill

These two Hallmark Channel starlets may not have ever shared the screen in romcoms, but during One Tree Hill, Lenz's character Haley hired Torrey DeVitto's Carrie to nanny her son Jamie in seasons 5 and 6.

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Carrie's angelic character quickly took a turn when her devious plot to break up Haley's family, win Nathan's heart, and act as a mother to Jamie was revealed before Dan ultimately killed her.

Huey Lewis As James "Jimmy" James

Huey Lewis on One Tree Hill

While Haley's large family is often talked about, they're rarely seen. But in season 2's "The Desperate Kingdom of Love," viewers are finally introduced to her parents, one of which was played by a well-known musician.

Huey Lewis, best known for leading his band Huey Lewis and the News and acting as the mastermind behind two hits on the Back to the Future soundtrack — one of the best '80s movie soundtracks — portrayed James "Jimmy" James for two episodes during which Haley asks for her parents' permission to marry Nathan.

Joe Manganiello As Owen Morello

Joe Manganiello on One Tree Hill

Not long before he was the memorable Alcide Herveaux on True Blood, Joe Manganiello scored a recurring role as troubled bartender Owen Morello from seasons 5 through 7 of One Tree Hill.

While Manganiello only appeared for a total of 13 episodes across three seasons, Owen managed Tric, became a Slamball player alongside Nathan, and had an on-again, off-again relationship with Brooke.

Evan Peters As Jack Daniels

Evan Peters on One Tree Hill

Evan Peters has become a phenomenon for his memorable role as Quicksilver in the X-Men franchise and for his spine-chilling characters in American Horror Story, but the actor got his star with minor appearances on TV shows, including a six-episode arc on One Tree Hill.

Peters played Jack Daniels, who is at the center of a dramatic storyline in which he and his best friend are held captive by Jack's only family member. Jack eventually leaves Tree Hill to go live with loving foster parents.

Lee Norris As Mouth

Lee Norris on One Tree Hill

Less of a guest star and more of a recurring character for the first two seasons, Lee Norris played Marvin McFadden — better known to everyone as Mouth, the less cool friend of Lucas' who often acts as a sports announcer during both fun and competitive basketball games.

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Norris eventually graduated to main character status come season 3 and remained on the show until OTH's final season, a much different turn of events compared to his Boy Meets World days when his loveable character Minkus was hardly seen again after season 1.

Gavin DeGraw As Himself

Gavin DeGraw on One Tree Hill

It was majorly meta in season 1 when singer Gavin DeGraw made a guest appearance. Why? Because while One Tree Hill had many memorable music moments, Degraw's was next level for being the voice behind OTH theme song "I Don't Wanna Be" from seasons 1 through 4.

The singer appeared as himself in the season 1 episode "You Gotta Go There to Come Back", in which Peyton runs into him at a CD shop and, in a natural order of events, convinces him to perform at Karen's Café, where he sings the show's theme, which at the time doubled as a Billboard Top 40 chart-topper.

Sheryl Crow As Herself

Sheryl Crow on One Tree Hill

The season 1 episode rightfully titled "The First Cut Is the Deepest" saw special guest star Sheryl Crow appear as herself and perform the title song at Karen's Café for megafan Haley and her boyfriend, Nathan.

A side story throughout the episode is Haley's frustration over not snagging tickets to Crow's concert in Tree Hill, so she winds up absolutely starstruck when the singer wanders into the café Haley was just closing up and agrees to perform for some free coffee.

NEXT: How Brooke Davis Became the Best Character in ‘One Tree Hill’