SEK or Sek may refer to:
Organisations
- Federation of Swiss Protestant Churches (Schweizerischer Evangelischer Kirchenbund)
- SEK Studio, a North Korean animation studio
- Stagecoach in East Kent, a transportation company in England
- SEK (Germany) (Spezialeinsatzkommando), police tactical units of the German state police forces
- Hellenic State Railways (Sidirodromoi Ellinikou Kratous), a former Greek public sector entity
- Socialist Workers Party (Greece) (Sosialistikó Ergatikó Kómma), a political party in Greece
- Swedish Export Credit Corporation (Svensk Exportkredit)
People
- Sęk, a Polish surname
- Sek Henry (born 1987), American-Jamaican basketball player
- Seksan Sukpimai (born 1974), known as Sek Loso, Thai singer, songwriter and musician
- Samuel Edward Konkin III (1947–2004), known as SEK III, Canadian-American writer
Other uses
- Swedish krona (ISO 4217 currency code), the currency of Sweden
- Sehk or Sek, a village in South Khorasan Province, Iran
- Sewer Evil King, a fictional character in Okage: Shadow King