Main cast •
Ólafur Darri Ólafsson as Andri Ólafsson,
Siglufjörður chief of police (season 1),
Reykjavík detective (season 2-3) •
Ilmur Kristjánsdóttir as Hinrika Kristjánsdóttir, Siglufjörður police officer, later chief of police •
Ingvar Eggert Sigurðsson as Ásgeir Þórarinsson, Siglufjörður police officer (Season 1-2), murder victim •
Björn Hlynur Haraldsson as Trausti Einarssson, chief of the Reykjavik Bureau of Investigation • Elva María Birgisdóttir as Þórhildur, Andri and Agnes's older daughter, returns to Siglufjörður (Season 1-2) •
Nína Dögg Filippusdóttir as Agnes Eiríksdóttir, Andri's ex-wife, resides in Reykjavík •
Baltasar Breki Samper as Hjörtur Stefánsson, Dagný's boyfriend, who survived the fire; later married, supervisor at Siglufjörður factory (Season 1-2) • Guðjón Pedersen as Bárður, Hinrika's husband •
Salka Sól Eyfeld as Soffia, friend of Jóhanna • Júlia Guðrún Lovisa Henje as Perla, Andri and Agnes's younger daughter •
Katla M. Þorgeirsdóttir as Laufey Eiríksdóttir, Agnes's other sister •
Sigrún Edda Björnsdóttir as Kolbrún, Hrafn's wife, later a local politician
Introduced season 1 •
Þorsteinn Gunnarsson as Eiríkur Davidsson, Agnes's father •
Bjarne Henriksen as Søren Carlsen, ferry captain •
Þorsteinn Bachmann as Sigurður Gudmundsson, harbourmaster, Guðmundur's son •
Pálmi Gestsson as Hrafn Eysteinsson, Siglufjörður mayor, former police chief •
Jóhann Sigurðarson as Leifur, owner of the fish factory and María's father •
Steinunn Ólína Þorsteinsdóttir as Aldís Grímsdóttir, teacher, Sigurður's wife •
Hanna María Karlsdóttir as Þórhildur, Agnes's mother •
Ólafía Hrönn Jónsdóttir as Freyja, Hjörtur's mother •
Rúnar Freyr Gíslason as Sigvaldi, Agnes's new partner • Jasmín Dúfa Pitt as Jóhanna, Laufey's daughter • Vytautas Narbutas as Jonas Malakauskas, Lithuanian trafficker • Grace Achieng as Joy, a Nigerian girl • Marta Quental as Nishadi, Joy's younger sister •
Hans Tórgarð as Dvalin Knudsson, ferry engineer • Georg Leite de Oliveira Santos as Ayanike, ferry chef • Lilja Nótt Þórarinsdóttir as María, colleague of Hrafn, daughter of Leifur • Jón Pétursson as Maggi, María's child • Kristján Franklin Magnúss as Guðni, hotel owner • Magnús Ragnarsson as Friðrik Davíðsson, an MP • Sigurður Karlsson as Guðmundur, fisherman •
Eysteinn Sigurðarson as Hjálmar, a young man • Sigurður Skúlason as Rögnvaldur, man in a wheelchair • Jóel Sæmundsson as Þór Snædal, Trausti's colleague •
Arnar Jónsson as Ævar, a senior Reykjavik police officer • Guðrun Gísladóttir as Ragna, a TV journalist • Stefán Jónsson as Geirmundur Jónsson •
Rán Ísóld Eysteinsdóttir as Dagný Eiríksdóttir, Agnes's sister who died in a fire 7 years before series 1
Introduced Season 2 •
Sólveig Arnarsdóttir as Halla, Minister of Industry • Þorgeir Tryggvason as Gisli, Halla, Elin and Ólafur's brother • Steinn Ármann Magnússon as Ketill, Siglufjörður farmer, protests against the factory • Stormur Jón Kormákur Baltasarsson as Aron, Þórhildur's boyfriend •
Unnur Ösp Stefánsdóttir as Elin, Aron's mother and Halla, Gisli, and Ólafur's sister •
Guðjón Davíð Karlsson as Finnur, Aron's father •
Aron Már Ólafsson as Víkingur, son of Gisli and Steinunn, Siglufjörður factory worker •
Elva Ósk Ólafsdóttir as Steinunn, Vikingur's mother • Valdimar Örn Flygenring as Ólafur, Steinunn's husband, Halla, Gisli, and Elin's brother • Kingsford Siayor as Ebo,
Ghanaian worker at Siglufjörður factory • Arnmundur Ernst Björnsson as Stefán, Siglufjörður factory worker • Valur Freyr Einarsson as David, factory manager •
Dar Salim as Jamal Al Othman • Sigurbjartur Atlason as Skúli, Ketill's son • Vignir Rafn Valþórsson as Torfi, Skúli's brother
Introduced Season 3 •
Jóhann Kristófer Stefánsson as Ívar, a member an Icelandic cult called The Family whose murder is the catalyst for the season's investigation; previously Andri had suspected his involvement in the disappearance of his then-girlfriend Lina •
Haraldur Stefánsson as Gunnar the estranged son of Oddur Jacobson, patriarch of The Family, and a former friend of Ivar. A member of his uncle's Hopper biker gang The Horns •
Thomas Bo Larsen as Danish Hopper, the violent leader of the biker gang The Horns; also wanted for his role in a methamphetamine racket •
Egill Ólafsson as Oddur Jacobson, a naturalist and leader of the cult, The Family; father of Gunnar •
Christina M Goldstein as Lina, a missing girl; the sister of Bergur and former girlfriend of Ivar •
Friðrik Róbertsson as Flosi, a young, misguided member of Gunnar's biker gang •
Emil B. Kárason as Logi, Hinrika's nephew •
Baldur T. Hreinsson as Kristjan, Ivar's father •
Halldóra Björnsdóttir as Magdalena, Ivar's mother •
María Pálsdóttir as Sigrún, a mortician •
María Thelma Smáradóttir as Elisabeth, a biker in Gunnar's gang •
Íris Tanja Flygenring as Freyja, Danish Hopper's girlfriend •
Heiddis Chadwick Hlynsdóttir as Dalla, another member of Gunnar's gang; Elisabeth's girlfriend •
Glódís Erla Ólafsdóttir as Eva, Gunnar's stepsister •
Skúli Gautason as Örn, police chief superintendent •
Snæfriður Ingvarsdóttir as Hrönn, a member of The Family who's attacked by The Horns •
Kara Ingudóttir as Sóley, a waitress at Bergur's bar and Ivar's current girlfriend •
Sigurður Þór Óskarsson as Bergur, a drug dealer working as a barista; brother of Lina •
Margrét Vilhjálmsdóttir as Asa, matriarch of The Family; having an affair with Ivar •
Atli Rafn Sigurðsson as Snorri, a member of The Family •
Ingibjörg Stefánsdóttir as Rósa, a member of The Family •
Davíð Guðbrandsson as Sverrir, Bergur's boyfriend and an informant reporting on Danish Hopper •
Hannes Óli Ágústsson as Baby Lars, a member of The Horns and Hopper's righthand man •
Svandís Dóra Einarsdóttir as Sonja, chief of the narcotics division; investigating Danish Hopper •
Arnar Dan as Haraldur, a narcotics cop •
Björn Jörundur Friðbjörnsson as Ísak, a cop •
Davíð Þór Katrínarson as Hákon ==Episodes==