Gun Metal Grey is a 2010 Hong Kong police procedural television drama produced by Television Broadcasts Limited. It originally aired on Jade from 1 November to 10 December 2010, consisting of 30 episodes. Gun Metal Grey is a dramatisation and fictional telling of Hong Kong's top ten criminal cases, which tells about the complexities of human nature and the strangeness of truth.

Gun Metal Grey is written by Lau Choi-wan and Leung Yan-tung, with Terry Tong serving as the executive producer. The drama is one of two grand TVB productions to celebrate the channel's 43rd anniversary, the other being No Regrets, both were the first to be broadcast live in English subtitles. The Chinese title of Gun Metal Grey literally means "criminal police", which can also be used to a describe a cop who commits a crime. During early promotions for the drama, the year "2010" was attached to the Chinese title to prevent confusion with previous dramas of a similar title. The English title is a wordplay on the colour of guns, a representation of criminal justice, and Felix Wong's character Stone Sir, a cop who finds himself trapped in a grey area of morality.