BTK may refer to:
- Baku-Tbilisi-Kars Railway
- Dennis Rader, a serial killer known as the "BTK killer"
- "Bind Torture Kill", a song by the band Suffocation on its album Suffocation.
- "Bind, Torture, Kill" is a song by the band Suicide Commando on its album Bind, Torture, Kill.
- Bacillus thuringiensis kurstaki, a strain of Bacillus thuringiensis controversial for its widespread use as an aerial spray against invasive gypsy moth populations.
- The Kaiser-Fleetwings XBTK, a dive and torpedo bomber developed for the United States Navy from 1944 to 1946
- The Bulgarian Telecommunications Company, abbreviated as БТК in Cyrillic and sometimes transliterated as BTK
- Bruton's tyrosine kinase, a protein whose mutation is associated with X-linked agammaglobulinemia
- Pillars of Truth (Boutokaan Te Koaua), a political party in Kiribati
- Birth Thru Knowledge, a Canadian hip-hop/rock band best known for the 1998 single "Peppyrock"
- Bilgi Teknolojileri ve İletişim Kurumu (aka Information And Communication Technologies Authority), Turkish Info&com regulatory body