Alexander M. Haig served as Secretary of State for Ronald Reagan was indeed a NATO commander .
Dwight D. Eisenhower became the first supreme commander of NATO : Supreme Allied Commander Europe (SACEUR) .
EISENHOWER
report to NATO's Supreme Allied Commander Europe prepare to conduct maritime strike and amphibious/expeditionary operations deter aggression against NATO members
The technicality is in the title within your question. The US President is the civilian "commander in Chief" of the US Armed Forces as stated in the US Constitution, however, during NATO supported conflicts, in the past, there has been a military position of Supreme Commander of NATO forces, which reports to the US President and NATO.
Gen Dwight Eisenhower was Supreme Commander of US Forces in Europe.He was Supreme Commander of NATO after that.
The NATO became a peacekeeping organization
The highest-ranking British military officer within NATO has been General Sir Nick Carter, who served as the Chief of the General Staff of the British Army and later became the Chief of the Defence Staff. He held the position of NATO's Supreme Allied Commander Transformation from 2018 to 2021. This role is crucial for shaping NATO's future military strategies and capabilities.
He became king and commander when he was 20.
The EU and NATO
Denmark and Norway.
Supreme Allied Commander, Europe (SACEUR)