One of the best things about popular TV shows is the guest stars. They can range from unknown actors who make it big to huge stars that show up and surprise everyone. Often times, the guest stars end up being the bad guy in the episode or storyline which they appear. A lot of the time, when someone joins the show who is not a part of the main cast, it is easy to guess that they will be a villain. It is a good way for shows to get ratings, but not always the best technique in terms of narrative. Here is a look at five celebrities who guest starred, only to come out as the villain.

Chris Rock ("Empire")

The comedian took a turn to the dark side in the latest season of “Empire.” Rock plays big-time criminal Frank Gathers, a man who runs a drug ring and can basically instill fear in anyone despite his wiry frame and comedic voice.

Rock’s character tries to kill off Cookie (Taraji P. Henson) because he believes she snitched on him about seeing him kill a man way back when. Gathers used to work with Cookie and Lucious (Terrence Howard) when they sold drugs back when Lucious was trying to get Empire off the ground.

Rock is not the type of actor that an audience would expect to take up the persona of a cannibalistic, killing-machine, drug king; but he is just that in the first episode of season two. His character does not last long however as he is taken care of by Lucious after Gathers threatens to kill Cookie and her family.

Paul Rudd ("Parks and Recreation")

Poor Paul Rudd. He is not really the bad guy, he just plays the goofy guy next door who happens to be placed in the villain role.

Rudd plays Bobby Newport, a rich kid who is thrown into the world of politics as he tries to become the newest City Council Member of Pawnee. Newport is a nice guy but he is incompetent and running against human fireball Leslie Knope (Amy Poehler) who will stop at nothing to take the seat in the city council.

Newport is very likeable and funny but he has no idea what he is doing. His charm and money alone help him become Knope’s main challenge in the election, but in the end he is no match for the powerful Leslie Knope.

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Brad Pitt ("Friends")

This one must be awkward now.

Back when Pitt was married to Jennifer Aniston, he guest starred on an episode of her popular series “Friends”

Pitt plays Will, a former high school classmate of Aniston’s character Rachel. Will has lost a lot of weight since high school and thus has gained the attention of Rachel. Too bad for Rachel, Will actually used to hate her in high school and he and Ross (David Schwimmer) actually started an “I Hate Rachel” club.

Due to his past hatred, Will is rude to Rachel throughout the episode which takes place at Thanksgiving dinner. It is also revealed that Will and Ross started a rumor that Rachel was a hermaphrodite.

James Franco ("General Hospital")

Back in 2009, James Franco sought out a role in a soap opera and came to an agreement with the show to play a serial killer by the name of Franco.

The character Franco was described as an artist whose canvas is murder. He is a strange man who sets out to kill Jason Morgan (Steve Burton). Franco goes about his weird obsession with killing Jason by terrorizing not only him, but his friends and family too. Jason eventually cannot take it anymore and when Fanco allegedly rapes Jason’s wife, Jason decides to kill the serial killer himself.

Being a soap opera, there was a story line after the death that Franco was actually Jason’s twin brother. Strange stuff.

Franco’s death marked the end of James Franco’s time on the show but not the end of Franco the character. Also being a soap opera, it is revealed that Franco is indeed not dead and he comes back as a major contributor to the show today.

Justin Bieber ("CSI")

What do you mean? Where are you now?

Back before the Biebs was asking questions to his many fans, he left his fans with one big question, What are you doing on “CSI”?

Bieber played a serial killer named Jason McCann who was out for revenge against cops because his adopted father raised him to believe that the government was corrupt.

Jason first bombed a police funeral where he killed two officers and then he ends up killing a homeless man on the streets.

Jason kills a few more people and makes a lot of threats before he ultimately dies in a shootout with some of the cops he was trying to kill.

Reach Staff Reporter Noah Camarena here and follow him on Twitter here.