Spiral (French: Engrenages, lit. 'Gears', pronounced [ɑ̃ɡʁəˈnaʒ]) is a French television police procedural and legal drama series following the work and the private lives of Paris police officers, lawyers and judges at the Palais de Justice, Paris. It was created by Alexandra Clert for the TV production company Son et Lumière. The first series of eight episodes started broadcast on Canal+ in France in December 2005.

The first series was shown in the UK on BBC Four during the summer of 2006. It was the channel's first French language drama series, attracting firm critical approval and a loyal audience of around 200,000. The second series, also eight episodes, was broadcast in France starting in May 2008, and in the UK on BBC Four starting in September 2009. The third series consisted of 12 episodes and was shown from April 2011. The fourth series was broadcast in February 2013. The fifth was broadcast in France in late 2014 and in the UK on BBC Four from January 2015. The sixth series was broadcast in 2017. The seventh series was broadcast in France in February 2019. Series four, five, six, and seven each consisted of 12 episodes.

The eighth and final series of ten episodes was broadcast on BBC Four in the UK during January 2021.

Spiral has been an export success, with sales to broadcasters in more than 70 countries including Australia, Denmark, Finland, Italy, Japan, Mexico, Portugal, Switzerland, Spain and the United Kingdom. In Australia, the first series was broadcast in 2008 on SBS One, the second series on SBS Two from September 2009 and the third series on SBS Two from mid-2012. Spiral debuted in North America via Netflix in September 2012, but subsequently dropped it. As of 2025, the series has been aired on MHz+.

Spiral has received wide-ranging critical acclaim throughout its run, and has been nominated for and won several awards.