With Adam Levine joining "American Horror Story," Miley Cyrus appearing on "Two and a Half Men," and Justin Bieber swinging by for a cameo on "The Simpsons," this fall TV season is going to be overwhelmed with musicians. Even Adam Lambert is returning to television -- for the "Pretty Little Liars" Halloween special -- and Snow Patrol's Gary Lightbody will be showing up on the next "Game of Thrones" season.
In honor of a fall schedule filled with music and TV crossovers, we've put together a list of the most painful small screen transitions that musicians have ever made. From Pete Wentz's time on "One Tree Hill," to Usher's minute on "Sabrina," to Britney Spears' one-off on "Glee," here are the 15 musical cameos that go down in history as TV's worst.
Katy Perry - "How I Met Your Mother"
"How I Met Your Mother" has had several entertaining, perfectly-timed cameos over its seven seasons. But Katy Perry's appearance, as the ditzy-but-pretty "Honey" whose real name Ted couldn't seem to remember, was not one of them. Her portrayal as a gullible (or "dumb," as Neil Patrick Harris put it) blind date for Ted -- who later found herself in Barney's bedroom -- bordered on annoying, and the cast's constant repetition of "Oh, Honey" every time Perry opened her mouth was too much to handle.
Usher - "Sabrina the Teenage Witch"
When Sabrina wanted to tell her boyfriend "I love you," who did she go to for help? Usher, a.k.a. "The Love Doctor," of course. The singer's few lines made us laugh (and cringe), but luckily the mood wasn't completely ruined -- Usher closed out the scene by doing what he does best, crooning with a trio of backup singers (who dressed up as sexy nurses… just because they could).
Pete Wentz - "One Tree Hill"
All of Fall Out Boy guest starred on the third season of "One Tree Hill," but it was Pete Wentz's multi-episode arc as Peyton's rockstar love interest that goes down in history as one of TV's worst cameos. Whether he was putting on his makeup alongside the ladies of Tree Hill or looking emo as a Fall Out Boy song played in the background, Pete's cameo felt forced and awkward. It's a toss-up which part of the episode was more hilarious: when Peyton called Pete a "famous rockstar" or when she quoted his "Pros and Cons of Breathing" lyrics before they started making out. The break-up came after a few episodes -- including one titled "I Slept With Someone In Fall Out Boy And All I Got Was This Stupid Song Written About Me" -- and "One Tree Hill" returned to the angst-ridden teen drama that would last for nine seasons.
Nick Jonas - "Smash"
The youngest JoBro's performance of Michael Buble's "Haven't Met You Yet" was one of the season's musical highlights, but his acting (and affected accent) was a flop. Nick Jonas' cameo didn't fit into the season's storyline, and he was forced into too many scenes: giving financial advice, hitting on the show's blonde bombshell lead, acting like a spoiled celebrity teen. We're glad the Jonas Brothers have been working on a new album -- they're better off in the studio than on the small screen.
Lance Bass - "7th Heaven"
'N Sync's Lance Bass had a short role on the 4th season of "7th Heaven," guest starring as Rick Palmer, Lucy Camden's short-term love interest and blind date. Watching Bass' uncomfortable, lackluster performance was painful in 2000, but now it's just funny. Plus we finally understand why  he and Lucy never made a convincing couple all those years ago...
Chris Brown - "The O.C."
Chris Brown has reportedly been looking for acting gigs lately, but if his role on "The O.C." is all casting directors have to go on, he won't be back on the small screen any time soon. Brown played straight-A student and "friend" to spoiled brat Kaitlyn, a storyline that would have been convoluted enough with a seasoned actor. Although the writers tried to give Brown some personality -- his character sabotages Kaitlyn in front of the whole class -- he has absolutely no emotion (a problem he doesn't seem to have anymore) and makes every scene dull.
Billie Joe Armstrong - "Nurse Jackie"
Billie Joe Armstrong's morose (and unintentionally comedic) time on "Nurse Jackie" was short, but that doesn't mean it was sweet. After awkwardly meeting him while praying at church, Edie Falco brings the Green Day frontman home for some less-than-pious activities. It's an unconvincing couple and Armstrong delivers his lines with a stiffness that shows he's best in front of a crowd -- not a camera. Nurse Jackie hardly gets to know the man she's brought into her bedroom before the drugs they share do him in pretty quickly.
Jennifer Lopez - "Will and Grace"
Jennifer Lopez joined the cast of "Will and Grace" for a two-episode arc between seasons six and seven, but the short role was no "Maid in Manhattan." adding one more list item to her acting resume. In her time on the sitcom, J-Lo signed Megan Mullally's chest, hired Jack as one of her backup dancers, and performed her hit "Waiting For Tonight" at Karen's wedding. It wasn't the best line on the former "American Idol" judge's acting resume, and it fell flat against many of the show's hilarious cameos.
Gabe Saporta - "Gossip Girl"
It's hard to be the creepiest character on "Gossip Girl," but Cobra Starship and former Midtown frontman Gabe Saporta's portrayal of Zeke -- the sketchy drug dealer who starts macking on Serena's neck after hanging her a bottle of coke -- certainly earns him that honor. "I'm not really a cocaine-peddling slimeball; I just play one on TV," Saporta tweeted  after the episode aired. Good to know, Gabe. It was a short role that will hopefully never be reprised, but it's still making our skin crawl.
Aaron Carter - "Lizzie McGuire"
During the first season of Disney's "Lizzie McGuire," Hilary Duff and company snuck onto the set of Aaron Carter's new video, evading security and parents alike. The whole episode focused on the younger Carter brother, but he was nowhere to be seen for most of the show's 30 minutes. Toward the end, however, the blonde pop star popped in -- just long enough to give Lizzie a smooch. It was all one big promotion for his "I Want Candy" single, but it also worked wonders for his love life, as Carter and Duff went on to date for nearly two years.
Britney Spears - "Glee"
"Glee's" first Britney tribute was its most-watched episode, but the cameos by Spears herself left a lot to be desired. In Rachel's "…Baby One More Time" sequence, the pop star was barely noticeable, on screen for only a second to flip her hair as the hot substitute teacher. Later on, she's one of the McKinley High School cheerleaders, and in the third part of her cameo, Britney appears in "Me Against the Music," telling the other Brittany that she smells good. It's supposed to be a fantasy, but it's really just awkward, and definitely not the most effective use of Spears' talents.
Will.i.am - "Joan of Arcadi"
Will.i.am's name on "Joan of Arcadia" was "Three Card Monty Guy God," so that pretty much sums up how important his role was. In the over-acted 30-second cameo, the Black Eyed Peas frontman preaches to Joan about making her own choices and keeping her eyes open to the world around her. If you listen carefully, you can even hear a Will.i.am track playing quietly behind the dialogue.
Snoop Dogg - "90210"
As much as Snoop Dogg's cameo on season two of "Weeds" can go down as one of TV's best, his appearance on the third season of "90210" is one of the worst. Bragging about cars, complimenting Dixon's "'Rari" and driving through L.A. with a high schooler, playing his unreleased single -- without a joint in sight? We hardly believe that's what an afternoon with Snoop would look like.
Iggy Pop - "The Adventures of Pete & Pete"
Back in the early '90s, punk pioneer Iggy Pop appeared on a few episodes of Nickelodeon's cult classic series, "The Adventures of Pete & Pete." In the cheesy cameo, the veteran rocker played Michelle Trachtenberg's father, the aptly-named "Pop," who jumped on stage at the school dance to sing his daughter a song. Oddly enough, Iggy's cameo wasn't the only one in that episode of "Pete & Pete" -- the band that had been playing before he jumped on stage was led by a Luscious Jackson member.
Alice Cooper - "Monk"
It wasn't Alice Cooper's fault that his "Monk" cameo was one of the lamest moments on cable television. We personally blame the writers, and whoever booked the ill-fitting gig on the USA series. It didn't make sense within the episode -- yes, Monk was going crazy from the smell of garbage on the street of San Francisco, but that's no excuse -- and all the "School's Out" singer did was sit in a chair and snarl. Next time Cooper appears on a serial detective dramedy, we hope he's given a role with more grit. Or at least a few lines.
- Pop