The Olenyok (Russian: Оленёк, sometimes spelled Оленек, Olenek; Yakut: Өлөөн, Ölöön) is a major river in northern Siberian Russia, west of the lower Lena and east of the Anabar.

It is frozen for over eight months every year and the climate in its area is harsh because of the direct influence of the Arctic.

[3] Pioneering Russian Arctic explorer Vasili Pronchishchev and his wife Tatiana (Maria) died of scurvy in the area of the river in September 1736, while mapping the coasts of the Laptev Sea.

[4] In 1956 the Olenekian Age of the Triassic Period of geological time was named for rock strata in the Olenyok area.

In its lower course it bends northwestwards skirting the western slopes of the Kystyk Plateau and the Chekanovsky Ridge before emptying into the Olenyok Gulf of the Laptev Sea.