Isilkul, or Isil'kul' (Исильку́ль in Russian), is a town in Omsk Oblast, 120km west of Omsk, population approx 28,000. It is a transfer point on the southern branch of the Trans-Siberian between Western Siberian and Sverdlovsk railroads.

Isilkul's name is of Central Asian origin, possibly meaning "enchanted lake".