2015 (MMXV) was a common year starting on Thursday of the Gregorian calendar, the 2015th year of the Common Era (CE) and Anno Domini (AD) designations, the 15th year of the 3rd millennium and the 21st century, and the 6th year of the 2010s decade.
In the time travel film Back to the Future, Part II, Doc Brown, Marty McFly, and Marty's girlfriend, Jennifer Parker, travel to October 21, 2015, to prevent some problems with Marty and Jennifer's future children. Jennifer is knocked out with a sleep-inducing alpha-rhythm generator, and remains asleep for the rest of the movie, until Back to the Future, Part III.