Claudio Descalzi is the chief executive officer of 📝Eni, the Italian multinational energy company, a position he has held since 2014. An 🏷️#executive who joined Eni as a reservoir engineer in 1981, he has directed the company's long-term decarbonization strategy, under which Eni became the earliest and heaviest oil-major investor in 📝fusion energy.

Descalzi is the partner executive most continuously present across 📝Commonwealth Fusion Systems' history. He was quoted at the company's 2018 launch out of the 📝MIT Plasma Science and Fusion Center, when Eni committed $50 million as CFS's first major outside backer; again at the 2021 Series B; and again in September 2025, when Eni signed an offtake agreement valued at roughly $1 billion for power from 📝ARC. On that agreement he framed the shift in terms of industrial maturity rather than research promise: "This strategic collaboration marks a turning point in which fusion becomes a full industrial opportunity."