Ogilby's duiker (Cephalophus ogilbyi), is a small antelope found in Sierra Leone, Liberia, Ghana, southeastern Nigeria, Equatorial Guinea's Bioko Island, and, possibly, Gabon. Two subspecies are recognized:

The third subspecies, Cephalophus ogilbyi brookei, is now considered to be a distinct species, Brooke's duiker.

Ogilby's duikers weigh up to 20 kilograms and have a shoulder height of up to 56 centimeters. They vary in color from chestnut to mahogany to a deep brown, and have massive hindquarters typical of duikers.

Ogilby's duikers live mainly in high altitude rainforest where they feed mainly on fallen fruit.

The total population is estimated at 30,000 individuals, with 12,000 C. o. ogilbyi and 18,000 C. o. crusalbum.