Sidious is a British black metal band from London, England, formed in 2012. They are known for evolving from symphonic blackened death metal roots into a more raw, aggressive, and atmospheric black metal sound.

Initially blending symphonic elements with blackened death metal on early releases, the band shifted toward a more direct, raw black metal approach with strong melodic and atmospheric qualities. Their music features blistering riffs, harsh vocals, epic structures, and a focus on themes of blasphemy, nihilism, evil, and darkness. They have built a solid reputation in the UK underground through consistent releases and live performances.