Nektarios Papantoniou was born in Athens in 1981. He entered the Hellenic Military Academy in 1998 and graduated in 2002 as a 2nd Lieutenant with the Armor Corps. He served in many different locations all over Greece, in both commanding positions and as a staff officer, such as in Main Battle Tank Battalions, in a Reconnaissance Battalion, in the Armor School as an instructor, in the Armor Simulation Center, in Armor Brigades and the Armor Directorate. He has successfully completed numerous military trainings both locally and in the US Army Armor School, up to the Hellenic Supreme Joint War College. He has also successfully completed additional studies and was awarded a MSc by Research Degree on Computational Fluid Dynamics (CFD) by Cranfield University, in the UK, and a MSc Degree on Autonomous Systems by the University of West Attica, in Athens. In 2024 he resigned his commission in the Army and went into the private sector Research and Development, as a Capability Development Expert with Milrem Robotics. He is fluent in English and has basic knowledge of German. He is married and currently resides in Athens.