The Williams FW16 is a Formula One car designed by Adrian Newey for the British Williams team. The FW16 competed in the 1994 Formula One season, with Williams winning the Constructor's Championship, and British driver Damon Hill finishing runner-up in the Drivers' Championship. It is notable as the last car to be driven by three-time world champion Ayrton Senna before his fatal accident during the San Marino Grand Prix. The car was designed around the major regulation changes that the FIA had introduced in the off-season, banning the various electronic devices that had been used by the front running cars during the preceding two seasons.

The FW16 was a passive evolution of the FW15C that had preceded it. It featured revised bodywork, including a low profile engine cover; taller sidepods; enclosed driveshaft; and an anhedral rear wing lower element, which was previously hinted at on the FW15C. In addition to these changes, the FW16 featured an innovative rear suspension wishbone design, an improved version of the Renault Sport Formula One engine (RS6), and a fuel valve to enable the ability for mid-race refuelling (a rule reintroduced for 1994).

As with the previous season, the number 0 car was driven by Damon Hill for the entire year. Only the defending champion had the right to use number 1 and reigning champion Alain Prost had left the sport. The number 2 car was driven by Ayrton Senna. Williams test driver David Coulthard filled in for most of the season but Williams also brought back Nigel Mansell, who had won the drivers' title for them in 1992, when his Indycar commitments allowed. Although it was fast, the car proved to be a tricky proposition in early testing and in the early part of the season. The car had a number of problems that were not properly remedied: it was aerodynamically unstable, and a design flaw was discovered in the car's frontal section and there were attempts to correct this in time for the ill-fated third race, at the San Marino Grand Prix.

Various other alterations were made by Newey and Patrick Head to alleviate the car's handling problems, such as the addition of bargeboards at the Spanish Grand Prix; the FIA-mandated modifications to the airbox at the Canadian Grand Prix; and shorter sidepods at the German Grand Prix. This heavily revised B-spec car was labelled the FW16B from the German race onwards and was much improved from the original car. It was developed by Hill, but the Benetton B194 and Michael Schumacher were dominant in the first half of the season.

The car configuration included a distinctive anhedral rear wing lower element, the effectiveness of which depended on a low outboard tail section, which was achieved by totally enclosing the driveshafts within wing-section carbon-fibre composite shrouds that doubled as the upper wishbones. This shroud was removable in case it was deemed to be outside the imposed regulations.

The car was powered by a 67-degree V10 engine by Renault Sport termed the RS6 specification, delivering approximately 830 hp. Its power was transmitted by means of a revised and lightened version of the six-speed transverse sequential gearbox used the previous year.

The FW16 featured power-assisted steering, hydraulically driven, and reacting to input from electronic sensors, a system that drew heavily from the knowledge gained from the team's active suspension technology. It lacked the fully-automatic gear change system of the preceding year and was restricted to a semi-automatic transmission. In accordance with the new 1994 regulations, the FW16 did not have adjustable anti-roll bar controls accessible by the driver from the cockpit, which were present in FW15C and earlier Williams F1 cars.

The early season performance of the FW16 indicated that it had shortcomings. The window of setup in which the car was competitive was very narrow, with many external factors which would otherwise be unrelated to the mechanics of the car (weather, track conditions, etc.), having unusually large influences on the overall performance. The early problems led to a raft of aerodynamic changes in the first half of the season, the first coming for the ill-fated San Marino GP at Imola. The front wing was a significant area of development. "The problem is that the front wing is too sensitive to the ride height," said Patrick Head in 1994. "If you were in a corner and went over a bump, the car could pick up a lot more front downforce than the rear. So if you were balanced at that point, with the car neutral, you'd lose the rear very quickly."