Christian Michael Leonard Slater (born August 18, 1969) is an American actor. He made his film debut playing a leading role in the 1985 film The Legend of Billie Jean. He then played a monk's apprentice alongside Sean Connery in The Name of the Rose before gaining recognition for his breakthrough role in the cult film Heathers. In the 1990s Slater featured in many big budget films including Robin Hood: Prince of Thieves, Interview with the Vampire: The Vampire Chronicles, Broken Arrow and Hard Rain. He was also featured in the cult film True Romance. Since 2000 Slater has combined work in the film business with television, including appearances in The West Wing and Alias. Slater was married to Ryan Haddon between 2000 and 2005; they had two children together. Slater has had widely publicized brushes with the law, including being sentenced to three months in jail for assault in 1997.

Christian Slater plays as Harry Morgan in Dexter: Original Sin.
Christian Slater is the top #1 member of the cast and appears in 1 episodes.

Michael C. Hall (born February 1, 1971) is an American actor whose television roles include David Fisher on the HBO drama series Six Feet Under and Dexter Morgan on the Showtime series Dexter. In 2009, Hall won a Golden Globe award and a Screen Actors Guild Award for his role in Dexter.

Michael C. Hall plays as Dexter's Inner Voice (voice) in Dexter: Original Sin.
Michael C. Hall is the top #2 member of the cast and appears in 1 episodes.

Christina Milian (born Christine Marié Flores, September 26, 1981) is an American recording artist, actress, dancer, and model. She moved to Los Angeles when she was 13 years old, desiring to be an actress. By the age of 17, she had begun writing songs to help obtain a recording contract. She has released three studio albums, and is currently working on fourth studio album due for release in 2011. Her self-titled debut album was released in 2001, and features the singles "AM to PM" and "When You Look at Me"; both peaked in the top three on the UK Singles Chart. Her second studio album, It's About Time (2004), provided her first major US hit "Dip It Low". Her third studio album, So Amazin' (2006), produced only one single, "Say I". A month after the release of So Amazin', her representative confirmed that she had left Island Records due to creative differences. She signed with Interscope Records in 2009, through which she will release her album, Elope. A single, ballad "Us Against the World", was released in October 2008. Although she is best known for her singing career, she originally wanted to be an actress. Her first lead role was in the 2003 film Love Don't Cost a Thing, and subsequently had main roles in Be Cool and the horror film Pulse. She had a minor role in Ghosts of Girlfriends Past, and starred as the lead role in the straight-to-DVD film Bring It On: Fight to the Finish. She has also starred in a number of TV movies. On September 4, 2009, she and R&B singer/songwriter The-Dream eloped in Las Vegas, and she gave birth to their daughter, Violet, on February 26, 2010. She and The-Dream announced their separation on July 12, 2010.

Christina Milian plays as Maria LaGuerta in Dexter: Original Sin.
Christina Milian is the top #3 member of the cast and appears in 1 episodes.

Patrick Galen Dempsey (born January 13, 1966) is an American actor and race car driver. He is best known for his role as neurosurgeon Derek "McDreamy" Shepherd in Grey's Anatomy. He had early success as an actor, starring in a number of films in the 1980s, including Can't Buy Me Love (1987) and Loverboy (1989). In the 1990s, he mostly appeared in smaller roles in film, such as Outbreak (1995) and television. Dempsey was also in Scream 3 (2000) where he played the role of Detective Mark Kincaid. He was successful in landing a lead role in Sweet Home Alabama (2002), a surprise box office hit. He has since starred in other films, including Brother Bear 2 (2006), Enchanted (2007), Made of Honor (2008), Valentine's Day (2010), Flypaper (2011), Freedom Writers (2007), Transformers: Dark of the Moon (2011), and Bridget Jones's Baby (2016). Dempsey, who maintains a sports car and vintage car collection, also enjoys auto racing in his spare time. He has competed in pro-am events such as the 24 Hours of Le Mans, Rolex 24 at Daytona sports car race, and Ensenada SCORE Baja 1000 off-road race. Prior to the 2013 24 Hours of Le Mans, Dempsey declared that he would "walk away" from acting if he could and dedicate himself full-time to motorsports.

Patrick Dempsey plays as Aaron Spencer in Dexter: Original Sin.
Patrick Dempsey is the top #4 member of the cast and appears in 1 episodes.

Roy "Reno" Wilson (born January 20, 1969) is an American actor.

Reno Wilson plays as Bobby Watt in Dexter: Original Sin.
Reno Wilson is the top #5 member of the cast and appears in 1 episodes.

James Martinez is an American stage and screen actor who attended The Juilliard School for Dramatic arts. He has performed on various Off Broadway stages and is known for guest roles in film and television.

James Martinez plays as Angel Batista in Dexter: Original Sin.
James Martinez is the top #6 member of the cast and appears in 1 episodes.

Patrick Leo Kenny-Gibson (born 19 April 1995 in Westminster, London, England) is an Irish actor known for his roles in The Tudors, The Passing Bells, and The OA. He was awarded Rising Star at the 2017 IFTAs. Gibson was born in central London. His father is also an actor and his mother works in marketing. Upon returning to Ireland, the family lived in Greystones, then Stillorgan, and later Donnybrook. Gibson attended Gonzaga College. He began his studies in Philosophy at Trinity College Dublin, but left halfway through his degree in 2016 upon being cast in The OA.

Patrick Gibson plays as Dexter Morgan in Dexter: Original Sin.
Patrick Gibson is the top #7 member of the cast and appears in 1 episodes.

Molly Brown plays as Debra Morgan in Dexter: Original Sin.
Molly Brown is the top #8 member of the cast and appears in 1 episodes.

Alex Shimizu plays as Vince Masuka in Dexter: Original Sin.
Alex Shimizu is the top #9 member of the cast and appears in 1 episodes.