The Sunbeam Tiger is a high-performance V8 version of the British Rootes Group's Sunbeam Alpine roadster, designed in part by American car designer and racing driver Carroll Shelby and produced from 1964 until 1967. Shelby had carried out a similar V8 conversion on the AC Cobra, and hoped to be offered the contract to produce the Tiger at his facility in the United States. Rootes decided instead to contract the assembly work to Jensen at West Bromwich in England, and pay Shelby a royalty on every car produced.

Two major versions of the Tiger were built: the Mark I (1964–1967) was fitted with the 260 cu in (4.3 L) Ford V8; the Mark II, of which only 633 were built in the final year of Tiger production, was fitted with the larger displacement Ford 289 cu in (4.7 L) engine. Two prototype and extensively modified versions of the Mark I competed in the 1964 24 Hours of Le Mans, but neither completed the race. Rootes also entered the Tiger in European rallies with some success, and for two years it was the American Hot Rod Association's national record holder over a quarter-mile drag strip.

Production ended in 1967 soon after the Rootes Group was taken over by Chrysler, which did not have a suitable engine to replace the Ford V8. Owing to the ease and affordability of modifying the Tiger, there are few remaining cars in standard form.

The Sunbeam Tiger was a development of the Sunbeam Alpine series I, introduced by the British manufacturer Rootes in 1959. Rootes realised that the Alpine needed more power if it was to compete successfully in world markets, but lacked a suitable engine and the resources to develop one. The company approached Ferrari to redesign the standard inline-four engine, recognising the cachet that "powered by Ferrari" would likely bring. Negotiations initially went well, but ultimately failed.

In 1962 racing driver and Formula 1 champion Jack Brabham proposed to Rootes competition manager Norman Garrad the idea of fitting the Alpine with a Ford V8 engine, which Garrad relayed to his son Ian, then the West Coast Sales Manager of Rootes American Motors Inc. Ian Garrad lived near Carroll Shelby's Shelby American operation, which had done a similar V8 conversion for the British AC Cobra.

According to journalist William Carroll, after measuring the Alpine's engine bay with "a 'precision' instrument of questionable antecedents" – a wooden yardstick – Ian Garrad despatched his service manager Walter McKenzie to visit the local new car dealerships, looking for a V8 engine that might fit. McKenzie returned with the news that the Ford 260 V8 engine appeared to be suitable, which apart from its size advantage was relatively light at 440 lb (200 kg). Ian Garrad asked Shelby for an idea of the timescale and cost to build a prototype, which Shelby estimated to be eight weeks and $10,000. He then approached Brian Rootes, head of sales for the Rootes Group, for funding and authorisation to build a prototype, to which Brian Rootes agreed.

Well all right, at that price when can we start? But for God's sake keep it quiet from Dad [Lord Rootes] until you hear from me. I'll work the $10,000 (£3,571) out some way, possibly from the advertising account.

Ian Garrad, impatient to establish whether the conversion was feasible, commissioned racing driver and fabricator Ken Miles to build another prototype as quickly as he could. Miles was provided with a budget of $800, a Series II Alpine, a Ford V8 engine and a 2-speed automatic transmission, and in about a week he had a running V8 conversion, thus proving the concept.