The original cast featured Johannes Brandrup as Frank Stolte and Rainer Strecker as Ingo Fischer. Fischer left the series just two episodes later and his replacement became Erdogan Atalay as Semir Gerkhan.

Brandrup quit the series at the end of Season 1. The television netwok RTL, which carries the series, contracted Mark Keller as André Fux in his place. Keller left the series at the end of Season 6 and was replaced by René Steinke as Tom Kranich. He played the role between the seasons 7-14, then decided to quit to try other roles.

Atalay's new partner became Christian Oliver as Jan Richter in Seasons 14-16. When he left the series to build his career in the US, RTL turned to Steinke, who agreed to return at the beginning of Season 17. However, Steinke decided not to renew his contract, and left the series again at the end at Season 20.
His replacement is actor Gedeon Burkhard as Chris Ritter. Burkhard is best known for his role in another German police show, Kommissar Rex.

In 2008 Burkhard is replaced by Tom Beck.

Semir is the main character and one of the cops who stayed on the force from the beginning to the end. He is best known for driving his silver BMW 3 series undercover car throughout his career. He also owns numerous exotic cars outside of work but had terrible things happen to them. (BMW crashed, Ferrari 355 spyder stolen). He is serious and will do whatever it takes to get the job done.

Tom is one of the more outgoing guys on the force, while Semir is serious. Together both of them gets the job done properly, sort of. He also have a forgiving personality due to the fact that he forgave a female driver despite that she wrecked his mountain bike on his first day commute to work. He also owns a Mercedes-Benz CLK 320 coupe, which is wrecked a dozen times.

Chris, who was originally a backup officer for Semir and Tom, became Semir's partner after Tom died in the episode "Auf Leben Und Tod". With the new partner the adventure continues, Chris drives a blue Mercedes-Benz CLK 320 which is the same one as Tom and in season 23 he started driving a gray Mercedes-Benz C350. His off work car is unknown.

Dida serves as the cobra team's backup officer throughout his career, his partner is an obese, bearded german, whose name is unknown. They drive a green and white "Polizei" porsche 911 turbo highway patrol car.

Jan was Semir's partner before he left the force, he was introduced in the episode "Feuertaufe" shortly after Tom's emotional withdraw. He is cowardly at first, even too scared to make a proper lane change. But he later got the hang of it and brings semir out of many dangerous situations. He left the force shortly after and semir was forced to look for Tom again. Tom agreed to go back and he was killed in action shortly after.

In 2008 two new faces make their debut in Cobra 11. First there is the new colleague of Semir: Ben Jäger, a role played by actor Tom Beck. Ben's first police-job was by the LKA and sees his job at the Autobahnpolizei only as a short unimportant job: he wants to get a better job at the police. That's way Semir and Ben don't like eachother. In the first case their have to transport a crown-witness. This witness is the only person who wants to talk about the criminalistic actions of Sander Kalvus, the murderer of Semir's former colleague Chris Ritter. During the transport Ben, Semir and the crown-witness are attacked several times by gangsters who want to kill the witness: an extreme baptism of fire for the new detective-duo. During the 13th season another new face appears in Cobra 11: boss Engelhardt quits her job after a case in which she discovers that she can't even trust a good colleague and friend. She is replaced by the new boss Kim Krüger, a role played by actress Katja Woywood. Kim has been informed about the manner of working of Ben en Semir en tries to get them to work in a different way, but if she succeeds....

The 13th season consists of a tv-movie and 14 epsiodes which were broadcasted in the autumn of 2008 and the spring of 2009 in Germany. A year later the 14th season is broadcasted in the same way. In the autumn of 2009 the first episode, also the 200st Cobra 11 episode, is broadcasted in Germany. This epsiode is the tv-movie "Das Ende der Welt" (The end of the world) in which Semir's gets to hear that he becomes father for the second time. But the joy about that is quick over when Semir and Ben are infected by a deadly virus. Will both find the anti-virus on time? As said the first episodes of the 14th season were broadcasted in Germany in the autumn of 2009. The other epsiodes followed in the spring of 2010.

In january 2010 the shootings for the 15th season have started. Also this season will start with a tv-movie. In "Der Anschlag" (The attempt) Ben and Semir are confronted with a criminal who wants to make attempts on cities in Germany with an explosiv new weapon. Can the detectives stop him on time? This tv-movie was broadcasted in Germany in september 2010 followed by six episodes. Six more epsides will be broadcasted in the spring of 2011 by the German tv-station RTL Television. The last episode of this season will broadcasted in the autumn of 2011.

In the TV movie of the sixteenth season an old-timer leaves the series. Actor Dietmar Huhn leaves Cobra 11: his character Horst Herzberger is shot. His empty place left in the Cobra 11 team is filled by agent Jenny Dorn, a role played by actress Katrin Heß. Already at the end of the fifteenth season she joins the Cobra 11 team and now is together with Bonrath responsible for the support of Ben and Semir. In the TV movie "72 Stunden Angst", partly recorded in Istanbul, we also get to know the unknown daughter of Semir. It turns out that he has a child from a previous relationship. His daughter Dana is kidnapped and Semir is committed to free her from the arms of the kidnappers. The sixteenth season consists of the mentioned TV movie and 14 episodes. The season was broadcast in autumn 2011 and spring 2012 on RTL Television.