The fourth and final series of the BBC television series Sherlock premiered in 2017.
Series 4 began with The Six Thatchers, broadcast on 1 January 2017. It continued with The Lying Detective and concluded with The Final Problem later that month. The three episodes formed the last regular series of the programme.
The fourth series followed a long gap after series 3, which had aired in 2014. Between them, Sherlock broadcast The Abominable Bride on 1 January 2016. That special used a Victorian-era framing story while connecting to the modern series’ continuing plot.
Although the programme ended its fourth series in 2017, its creators and cast have periodically discussed the possibility of returning. No fifth series has been broadcast. Therefore, 2017 identifies the premiere year of the final completed series, not necessarily a definitive statement about every future production possibility.