• Born year: 1924
• Born in: Fiji
• Death year: 1993
• Death in: Fiji

Siddiq Moidin Koya (1924–1993) was a Fijian Indian politician and Opposition leader. He succeeded to the leadership of the mostly Indo-Fijian National Federation Party (NFP) on the death of the party's founder, A.D. Patel, in October 1969, remaining in this post until 1977. He later served a second term as leader of the NFP, from 1984 to 1987.Koya is credited with his role in paving the way for Fijian independence from Britain in 1970.