Fender amplifiers are electric instrument amplifiers produced by the Fender Musical Instruments Corporation. The first guitar amplifiers attributed to Leo Fender were manufactured by the K&F Manufacturing Corporation (K&F) in 1945. Later, Fender began building its own line of electric guitars. Fender amplifiers would become favorites of guitarists like Jimi Hendrix, Eric Clapton, and Stevie Ray Vaughan, also known in these cases for playing Fender guitars.

Fender amps have come in many configurations and styles. The early K&F and Fender amplifiers relied upon vacuum tube circuitry, with solid-state models appearing in the late 1960s. Fender frequently updated the internal circuitry of its amps, and changed their appearance throughout its history.

The first "Fender" amplifiers were manufactured by Leo Fender and Doc Kauffman, doing business as the K&F Manufacturing Corporation. The amplifiers were housed in a steel case and most were finished in a "gray crinkle" finish that was baked in the Kauffman family oven. They were made in three sizes: 1×8" (one 8-inch speaker), 1×10", and 1×15". They are all very rare today and few have survived.

The first amplifiers made in-house by the Fender Electric Instrument Company were a significant step up in size and function to the small, nameless amps that preceded them, however, they didn't have technological advancements such as circuit boards in their designs. They were constructed out of spare hardwood held by the Fender company at the time and were hence given the name 'woodie' later on by collectors. These amps were the Princeton, the Deluxe and the Professional. The Princeton was a small six watt amp with an 8" Jensen field-coil speaker. This amp had no controls as it was designed for the guitar to solely control the volume and was simply turned on by plugging/unplugging into the wall plug. The Deluxe was a larger amp with a Jensen 10” field-coil speaker and five tubes in a 14-watt design. It was the most popular amp of this era, with most amps surviving from this era today being Deluxes. The rarest of all the original 'woodie' series was the Professional. It was the largest of the trio featuring Jensen 15" field-coil speaker and six tubes delivering 25 watts of power.

The production of these first amps ceased in 1948; however, their names have remained in use with new Fender amplifier lines.

In 1948 Fender entered a new phase of amplifier construction dubbed 'the tweed phase'. This phase saw the company drape their amplifiers in a cloth covering, which consists of varnished cotton twill. This is incorrectly called tweed because of its feel and appearance (actual tweed is a rough woolen fabric). The amps made during this period were a considerable leap forward for Fender, and they are often praised for their sound and their circuitry. Fender generally stopped using the twill covering in 1960, though the Harvard was still covered in twill until 1963, and the Champ until 1964.

At the beginning of the "tweed" era, Fender constructed many of its cabinets in "TV front" style, amps which bore a strong resemblance to TVs of the time. In 1955 they shifted to the "wide panel" design, a more conventional design where the top and bottom panels are wider than the side. Fender later constructed them with "narrow panel", in which all the panels have more or less the same width.

The Brownface series was introduced in 1959. The name 'brownface' stems from the brown-colored control panels, common to both the brown- and cream/blonde- Tolex-covered amps. The brownface amps originally featured a dark maroon or "oxblood" grillcloth, which was changed to "wheat" in 1962-63.