JJK may refer to:

• JJK Jyväskylä, a Finnish football team from the city of Jyväskylä
• John "Julius" Knight, American musician
• Jesper Kyd, Danish video game composer
• Jacqueline "Jackie" Joyner-Kersee, American former heptathlon athlete

• Guillermo Douglas
• Guillermo Díaz Gastambide
• Guillermo Díaz (Uruguayan footballer)
• Guillermo Díez-Canedo
• Guillermo Eduardo Landazuri Ricketts
• Guillermo Estevez Boero
• Guillermo Estrugo
• Guillermo Falasca
• Guillermo Farinas
• Guillermo Fariñas
• Guillermo Fariñas Hernández
• Guillermo Fayed
• Guillermo Fernandez-Shaw
• Guillermo Fernandez Vara
• Guillermo Fernández de Soto
• Guillermo Fernández Shaw
• Guillermo Fernández-Shaw
• Guillermo Fernández-Shaw Iturralde
• Guillermo Fernández Vara
• Guillermo Fesser
• Guillermo Ford
• Guillermo Franco (born 1983)
• Guillermo Franco (disambiguation)
• Guillermo Franco (Ecuadorian general)
• Guillermo Franco (football defender)