Altered is a former National Hot Rod Association (NHRA) drag racing class and a current drag racing chassis configuration that forms the basis of many classes of NHRA Competition Eliminator.

The altered is "[s]ometimes called the poor man's [d]ragster". While the emblematic altered is a short-wheelbase roadster with exposed engine and front frame rails, very similar to the earliest rail dragsters, altereds can be bodied cars also.

By definition, altereds were essentially stock gas, alcohol, or nitromethane-class cars with parts removed or changed, making them ineligible for the previous class, such as Keith Ferrell's Dogcatcher, a 1936 Willys sedan delivery; built as a gasser, Ferrell deliberately left something off to run it in B/Altered.

The Altered category originated "for cars with moderate changes", according to the rulebook. It developed from out of the Hot Roadster, Fuel Coupé, and Fuel Sedan categories. In 1956, it was divided in three classes by weight break: A (up to 6.59 lb/cu in (182 kg/L)), B (6.6–8.59 lb/cu in (183–238 kg/L)), and C (8.6 lb/cu in (240 kg/L) and up). Rules allowed moving the engine back up to 25% of the wheelbase, as well as chopping and channeling, which were prohibited in gassers. The class had few limits or requirements. One of the pioneers was Walt's Puffer II, an unsupercharged A/Altered Fiat Topolino powered by a 392 hemi, driven by Walt Knoch.

Of the early altereds, the #554 A Fuel Coupé (A/FC), a '34 five-window, was "[u]ndoubtedly the most famous". It was built in the middle 1950s and (campaigned by Mooneyham and Johnson, driven by "Jungle Larry" Faust) turned in a best pass of 133.60 mph (215.01 km/h) with full fenders in Street Coupé. As a hiboy, at Bakersfield in 1960, that went up to 148.27 mph (238.62 km/h); the next month, it was the first altered to exceed 150 mph (240 km/h), with a trap speed of 152.02 mph (244.65 km/h). That rose again in 1961, to 165.13 mph (265.75 km/h), and by the time the car was retired, it had a best pass of 8.98 at 170.00 mph (273.59 km/h). The #554 Coupé was powered by a supercharged 390 cu in (6.4 L) hemi (a 331 cu in (5.4 L) block) on between 40% and 75% nitro. It routinely filled the cockpit with smoke and burned rubber and clutch dust; track marshals once asked Faust if he needed help after exiting the smoking car, to which Faust casually replied, "Why? This thing does this all the time."

In 1957, NHRA banned nitro in all categories; the American Hot Rod Association (AHRA) still allowed it, and Fuel Dragsters (FD), Hot Roadsters (HR), and Fuel Coupés (FC), in the days before Funny Car, went there instead: it would be Drag News and their Standard 1320 record which christened them Fuel Altereds. AHRA grouped coupés and roasters together, unlike NHRA, under Hot Car Eliminator (HCE). Independent drag strips, not NHRA sanctioned, offered venues for the fuel racers. Smokers Car Club hosted the first U.S. Fuel and Gas Championship at Famoso Raceway in March 1959. Bob Hansen won Top Fuel Eliminator (TFE) in his A/HR, with a speed of 136 mph (219 km/h).

Early in the 1960s, as supercharging proliferated, NHRA added AA/A, BB/A, and CC/A. In 1956, the A/A class record holder, "Jazzy Jim" Nelson's '47 Topolino, was so quick, it would face dragsters in Top Eliminator at the end of meet.

Supercharged A fuel altereds, or AA/FAs, are exemplified by the famous Pure Heaven, Pure Hell, and Rat Trap.