The molecule that absorbs the emission of fluorescent reporter when in close vicinity (6 to 10 nucleotides). Commonly used quenchers include TAMRA (fluorescent), and non-fluorescent ones DABCYL and black hole quencher (BHQ) dyes. The quenchers are usually at the 3’ end of a dual-labeled fluorescent probe. Quencher dye is also called acceptor. A quencher’s efficiency increases as the spectral overlap of the reporter dye emission profile and quencher absorption profile increases (highest for BHQ).