Paul G. Allen, the co-founder of Microsoft who helped usher in the personal computing revolution and then channeled his enormous fortune into transforming Seattle into a cultural destination, died on Monday in Seattle. He was 65.

The cause was complications of non-Hodgkin’s lymphoma, his family said in a statement.

The disease recurred recently after having been in remission for years. He left Microsoft in the early 1980s, after the cancer first appeared, and, using his enormous wealth, went on to make a powerful impact on Seattle life through his philanthropy and his ownership of the N.F.L. team there, ensuring that it would remain in the city.

Mr. Allen was a force at Microsoft during its first seven years, along with its co-founder, Bill Gates, as the personal computer was moving from a hobbyist curiosity to a mainstream technology, used by both businesses and consumers.

When the company was founded, in 1975, the machines were known as microcomputers, to distinguish the desktop computers from the hulking machines of the day. Mr. Allen came up with the name Micro-Soft, an apt one for a company that made software for small computers. The term personal computer would become commonplace later.