The drugs were tested on people at high risk of heart disease
The finding is the result of a massive £21m study involving more than 20,000 volunteers and 69 hospitals across the UK.
All the volunteers were at high risk of coronary heart disease.
Not only did the drugs cut the risk of heart attack and stroke, they also reduced the need for arterial surgery, angioplasty and amputations.
Coronary heart disease kills more than 110,000 people a year in England. A major cause is cholesterol circulating in the bloodstream.
Lead researcher Professor Rory Collins said: "This is a stunning result, with massive public health implications.
"We've found that cholesterol-lowering treatment can protect a far wider range of people than was previously thought, and that it can prevent strokes as well as heart attacks."
Professor Collins said that if an extra 10m people world-wide were now prescribed statins, this would save about 50,000 lives a year.
Uncertainty
The study specifically targeted groups of patients in which there was little direct evidence of benefit - including women, the over 70s, people with diabetes, those with non-coronary vascular disease, and those with average or below-average cholesterol levels.
Not only were the benefits clear, there was no evidence of potentially harmful side effects such as damage to the leg muscle.
Volunteers were allocated either 40mg daily simvastatin as cholesterol-lowering therapy, or matching dummy tablets. Study treatment and follow-up continued for an average of five and a half years.
Professor Sir George Radda, chief executive of the Medical Research Council, said: "The results of this important seven year study are great news and will bring real benefits for the many people who are affected by cardiovascular problems.
"It is particularly good to know that through a single trial we have identified a whole new set of patients with a variety of conditions who can also be treated successfully with statins.
"The implications for managing health are good for patients and healthcare professionals alike."
Professor Sir Charles George, medical director of the British Heart Foundation, said the results were clear cut and could be widely applied.
"Statin therapy clearly benefits people previously thought unlikely to benefit from such treatment."
Vitamins
The researchers also examined whether giving patients vitamin supplements would have any positive effect. It did not.
There is a theory that vitamins A, C and E prevent the oxidation of fat in the walls of blood vessels - making it less likely that they will become clogged.
However, the research found no benefit at all from giving the so-called anti-oxidant vitamins to patients.
The research was carried out by Oxford University's Clinical Trial Service Unit by the same team that showed that aspirin can have a protective effect on the heart. It was co-sponsored by the British Heart Foundation and the Medical Research Council.
The findings were presented to a meeting of the American Heart Association in Los Angeles on Tuesday.
It is now likely that the use of statins will be considered by the independent NHS drug watchdog, the National Institute for Clinical Excellence.