Siku may refer to:

• Siku (instrument), a kind of pan flute from the Andes
• Siku (Bolivia), a mountain in the Bolivian Andes
• Siku Toys, a German brand of toy vehicles
• Siku (comics), an artist
• Siku (polar bear), a bear cub who became an overnight online sensation
• Siku Quanshu, a compendium of Chinese literature completed in 1782
• Secoo, Chinese online retailer
• Siku Allooloo, indigenous writer
• Siku Ya Bibi (Day of the Lady)
• Siku Njema, a Swahili novel