Bolshoye Ozero (; , Olokül) is a rural locality (a village) in Askinsky Selsoviet, Askinsky District, Bashkortostan, Russia. The population was 15 as of 2010. There are only 2 streets in the village.
Bolshoye Ozero is by road 24 km northwest of Askino (the district's administrative centre). Tulguzbash is the nearest rural locality.