10 crime series of varying length and type.
The amount of crime series out there is staggering, from retellings of true crimes to adaptations of crime fiction, or just crime series written directly for the screen. Their popularity is unbroken, and the various types and settings allow for interesting discoveries. Here are 10 crime series I enjoyed watching - some still ongoing.

American Crime Story (2016-) (3rd season coming in 2020)
True Crime series, always dealing with one crime per season. The first season, dealing with the O.J. Simpson case and trial, was outstanding. The second season followed the murderer of Gianni Versace, who also killed several other men before his most famous victim. Especially interesting is the upcoming season, which will tell the story of the Bill Clinton affair and impeachment - should be interesting to see the parallels to the recent impeachment of another president.
Starring: Cuba Gooding Jr., John Travolta & Sarah Paulson (1); Darren Criss, Penelope Cruz & Edgar Ramirez (2); Clive Owen, Beanie Feldstein & Annaleigh Ashton

Luther (2010-) (Five seasons so far)
A fictional series about a tough Detective Inspector in a Special Crimes Unit in London. Det. Luther uses unusual methods and is not fully in control of his private life either, but he is great at his job. Besides the great Idris Elba who carries this series, Ruth Wilson is a cunning antagonist as she has proven in many roles.
Starring: Idris Elba, Ruth Wilson, Indira Varma

The Wire (2002-2008) (Five seasons)
Often considered one of the original crime series that inspired many others, The Wire is set in Baltimore and shows a tough world. The series is unique for showing different perspectives of crime, both police and criminals and also uninvolved citizens that are affected. The drug scene is shown in a very realistic way, which sheds light on some realities in urban areas in the US.
Starring: Dominic West, Lance Reddick, Sonja Sohn, Wendell Pierce, Michael B. Jordan and countless other great actors

Mindhunter (2017-) (Two seasons so far)
True Crime series set in the 70ies, based on two FBI agents who are interested in developing patterns to help them understand serial criminals. They interview incarcerated offenders and try so use their findings to solve open cases. The series shown this interesting development, and includes many real criminals and cases. Created by renowned director David Fincher.
Starring: Jonathan Groff, Holt McCallany, Anna Torv

When They See Us (2019) (One season)
True Crime mini-series about the famous case of the "Central Park Five". Several African-American teenagers from Harlem are in the wrong place at the wrong time during a night in the 80ies, when woman gets brutally assaulted. The series shows all consequences of trials, prison sentences and vindication of this landmark case, with great performances under the direction of Ava DuVernay. A truly chilling and heartbreaking crime series because of its content and execution.
Starring: Jharrel Jerome, Asante Black, John Leguizamo, Felicity Huffman, Vera Farmiga and many more.

Sherlock (2010-) (Four seasons so far)
A series based on the greatest literary detective figure of all times, Sherlock Holmes. This series modernises the action from Victorian to contemporary London, and adds some interesting twists to the well known stories by Sir Arthur Conan Doyle. The depiction of Holmes as a high-functioning sociopath in our modern world is hilarious, mainly due to the great scripts and the outstanding performance by Benedict Cumberbatch.
Starring: Benedict Cumberbatch, Martin Freeman, Mark Gatiss, Ropert Graves, Amanda Abbington, Andrew Scott and many more.

The Sopranos (1999-2007) (Six seasons)
Fictional series about a mob boss from New Jersey and his family. A great performance by the late James Gandolfini, who managed to show different elements to a deeply conflicted figure. Besides being involved in horrible mafia business with threatening opponents, he still has to deal with his own family, and struggles so much that he starts seeing a psychotherapist. This unusual mixtures created plenty of comedy, and creates an unusual perspective of crime inside the mafia.
Starring: James Gandolfini, Lorraine Brasco, Edie Falco, Michael Imperioli, Jaime-Lynn Sigler, Drea de Matteo, Jerry Adler, Steve Buscemi and many more.
PS: A prequel film about Tony Soprano's youth is coming out in 2020.

Dexter (2006-2013) (Eight seasons)
An unusual series dealing with both solving and committing crimes, as the protagonist is both an analyst for the police department in Miami as well as a serial killer. Following a strict code of only killing bad people, Dexter is likeable enough for the audience to be on his side. Great writing and many suspenseful story lines with convincing guest stars such as John Lithgow, Colin Hanks and Charlotte Rampling.
Starring: Michael C. Hall, Jennifer Carpenter, David Zayas, James Remar, Luna Lauren Velez, Yvonne Strahovsky

Orange is the New Black (2013-2019) (Seven seasons)
A series based partially on a true story, as the protagonist Piper Chapman (in real life: Kerman) wrote a memoir about her experiences as a college-educated white woman, who was sent to prison after a drug-related offence. Rather naive and optimistic at first, she starts to realise that there are different rules in prison. The greatness of the series lies not even that much in this comedic storyline, but more so in the various destinies of the women around her. The series uses frequent flashbacks to tell the background stories of the women and how they ended up in prison, which is often heartbreaking.
Starring: Taylor Schilling, Laura Prepon, Uzu Aduba, Taryn Manning, Danielle Brooks, Dascha Polanco, Natasha Lyonne, Samira Wiley and many more.

True Detective (2014-) (Three seasons so far)
Crime series with a different plot and set of characters every season. Season one was one of the greatest collection of episodes ever, telling a gruesome story of mysterious crimes that seemed linked, and introducing a team fo detectives that was dysfunctional and charming. Unfortunately, which the concept has remained the same for other seasons, the first one has not been matched in level since. But the second and third season were still solid crime television.
Starring: Woody Harrelson & Matthew McConaughey (1); Colin Farrel & Rachel McAdams (2); Mahershala Ali & Carmen Ejogo (3)
Honorable Mentions:
Boardwalk Empire, Unbelievable, Jessica Jones, Broadchurch, Elementary, River, The Bletchley Circle, How To Get Away with Murder
(Images: IMDB)