Original description species: HODNETT, ELLIOTT, OLSON & WITTKE, 2012
Genus: Kaibabvenator HODNETT, ELLIOTT, OLSON & WITTKE, 2012
Family: incert. fam.
Order: Ctenacanthiformes
Superorder: Cladodontomorphi
Subclass: Elasmobranchii

Original description species: ENGELBRECHT, MÖRS, REGUERO & KRIWET, 2017
Genus: Kallodentis ENGELBRECHT, MÖRS, REGUERO & KRIWET, 2017
Family: Triakidae GRAY, 1851
Order: Carcharhiniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: MÄRSS & GAGNIER, 2001
Genus: Kannathalepis MÄRSS & GAGNIER, 2001
Family: Kannathalepididae MÄRSS & GAGNIER, 2001
Order: Elegestolepidida

Original description species: LEBEDEV, 2014
Genus: Kanodus LEBEDEV, 2014
Family: Psephodontidae JAEKEL, 1898
Order: Cochliodontiformes
Superorder: Holocephalimorpha
Subclass: Holocephali

Original description species: KOZLOV IN ZHELEZKO & KOZLOV, 1999
Genus: Karaisurus KOZLOV IN ZHELEZKO & KOZLOV, 1999
Family: Lamnidae MÜLLER & HENLE, 1838
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: MÄRSS, KLEESMENT & NIIT, 2008
Genus: Karksilepis MÄRSS, KLEESMENT & NIIT, 2008
Family: incert. fam.
Order: incert. sedis

Original description species: IVANOV & MÄRSS, 2011
Genus: Karksiodus IVANOV & MÄRSS, 2011
Family: incert. fam.
Order: incert. sedis
Subclass: Elasmobranchii

Original description species: GAGNIER & WILSON, 1996
Genus: Kathemacanthus GAGNIER & WILSON, 1996
Family: incert. fam.
Order: Climatiformes

Original description species: PRADEL, TAFFOREAU, MAISEY & JANVIER, 2011
Genus: Kawichthys PRADEL, TAFFOREAU, MAISEY & JANVIER, 2011
Family: incert. fam.
Order: Symmoriiformes
Superorder: Cladodontomorphi
Subclass: Elasmobranchii

Synonyms: Cetorhinus aff. parvus, Cetorhinus cf. parvus, Cetorhinus parvus, Praecetorhinus parvus, Selache parvus
Original description species: (LERICHE, 1908)
Genus: Keasius WELTON, 2013
Family: Cetorhinidae GILL, 1861
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: REINECKE, VON DER HOCHT & DUFRAING, 2015
Genus: Keasius WELTON, 2013
Family: Cetorhinidae GILL, 1861
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: REINECKE, VON DER HOCHT & DUFRAING, 2015
Genus: Keasius WELTON, 2013
Family: Cetorhinidae GILL, 1861
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: WELTON, 2013
Genus: Keasius WELTON, 2013
Family: Cetorhinidae GILL, 1861
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Cretolamna gunsoni
Original description species: (SIVERSON, 1996)
Genus: Kenolamna SIVERSON, LINDGREN, NEWBREY, CEDERSTRÖM & COOK, 2015
Family: Otodontidae GLICKMAN, 1964
Order: Lamniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: CUNY, SUTEETHORN, KAMHA & BUFFETAUT, 2008
Genus: Khoratodus CUNY, SUTEETHORN, KAMHA & BUFFETAUT, 2008
Family: Thaiodontidae CUNY, SUTEETHORN, KAMHA & BUFFETAUT, 2008
Superfamily: Hybodontoidea
Order: Hybodontiformes
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Galeorhinus aff. gomphorhiza, Galeorhinus gomphorhiza
Original description species: (ARAMBOURG, 1952)
Genus: Khouribgaleus NOUBHANI & CAPPETTA, 1997
Family: Triakidae GRAY, 1851
Order: Carcharhiniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: KOOT, CUNY, TINTORI & TWITCHETT, 2013
Genus: Khuffia KOOT, CUNY, TINTORI & TWITCHETT, 2013
Family: Sphenacanthidae MAISEY, 1982
Order: incert. sedis
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: KOOT, CUNY, TINTORI & TWITCHETT, 2013
Genus: Khuffia KOOT, CUNY, TINTORI & TWITCHETT, 2013
Family: Sphenacanthidae MAISEY, 1982
Order: incert. sedis
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Ischyrhiza cf. texana, Ischyrhiza texana, Kiestus texanus, Ptychotrygon ritchiei
Original description species: (CAPPETTA & CASE, 1975)
Genus: Kiestus CAPPETTA & CASE, 1999
Family: Sclerorhynchidae CAPPETTA, 1974
Suborder: Sclerorhynchoidei
Order: Rajiformes
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Original description species: UNDERWOOD & CLAESON, 2017
Genus: Kimmerobatis UNDERWOOD & CLAESON, 2017
Family: Spathobatidae UNDERWOOD, 2006
Superorder: Batomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Kneria mashkovae, Knerialepis cf. mashkovae
Original description species: (KARATAJUTE-TALIMAA, 1997)
Genus: Knerialepis HANKE & KARATAJUTE-TALIMAA, 2002
Family: incert. fam.
Order: incert. sedis
Subclass: Elasmobranchii

Original description species: LAURITO MORA, 1999
Genus: Kruckowlamna LAURITO MORA, 1999
Family: Carcharhinidae JORDAN & EVERMANN, 1896
Order: Carcharhiniformes
Superorder: Galeomorphii
Subcohort: Neoselachii
Cohort: Euselachii
Subclass: Elasmobranchii

Synonyms: Cobelodus obliquus
Original description species: (IVANOV, 2005)
Genus: Kungurodus IVANOV, 2016
Family: incert. fam.
Order: Symmoriiformes
Superorder: Cladodontomorphi
Subclass: Elasmobranchii