Marc Benioff, CEO of Salesforce.com, stands out as the pioneer and guerrilla marketer of software-as-a-service. He drew attention to the concept at a time when it was widely disregarded as an aberration of limited use by brazenly advancing the concept of cloud services as the "death of software." He meant that on-premises software, the systems that have been making enterprise data centers run since 1964, were going away, replaced by software running in a remote data center accessible over the Internet.
Much has already been written about the successful establishment of Salesforce.com, which doesn't need repetition here. But for his role in winning respect for the concept of SaaS, no one matches the standing of Benioff.