The Fender Twin Reverb is an all-tube guitar amplifier with two 12", 8 ohm speakers made by various suppliers. The more common speakers found in Fender Twin Reverbs include Jensen C12Ns, Oxford 12T6s, JBL D-120Fs, Utahs and, in later years, CTS and Eminence models. The Twin Reverb is frequently shortened in conversation to 'Fender Twin' or simply 'Twin', though it shouldn't be confused with the Tweed or Blonde era Twin amplifiers which had vastly different circuits and no reverb. The Fender Twin Reverb is considered a standard model for players seeking a clean sound, and it is especially known for the quality of its built-in spring reverb. All Twin Reverbs feature a solid state rectifier.

The Twin Reverb II was replaced by The Twin, commonly referred to as the "Evil Twin" due to its appearance and the addition of both a separate gain channel and a switchable overdrive on the clean, in 1987. It featured a dual output switch, allowing the user to select either 25 watts of output or 100 watts of output. The "Red Knob Twin" was made until 1994; it has since been succeeded by "Twin Amps" of Fender's current Protube