At just 15 years old, Zack O Leary, Grammar, has achieved one of the highest honours in global pre-college STEM competitions, winning first place in the Software Design category at the 2026 Regeneron International Science and Engineering Fair in Phoenix, Arizona.
Representing Ireland as the 2025 SciFest STEM Champion, Zack’s victory places him among the youngest major category winners at this year’s competition and marks a remarkable milestone for Irish science and engineering education.
Held at the Phoenix Convention Center, Regeneron ISEF is widely regarded as the world’s most prestigious science and engineering competition for secondary school students. The 2026 event brought together more than 1,700 finalists from around 70 countries, regions and territories, competing across 22 scientific categories for over $7 million in awards and scholarships.
Reaching the ISEF stage alone is an extraordinary achievement. Globally, millions of students begin the qualification journey each year through regional, national and affiliated science fairs, with only a tiny fraction progressing to the international final. Estimates place the acceptance rate at well below 0.1%, making finalist status itself one of the most selective honours in student STEM research.
Zack earned his place in Phoenix after winning the overall SciFest STEM Champion title in Ireland in 2025 for his project M.A.N.T.I.S — “Muon Analysis for Non-Invasive Tomography and Image Simulation.” SciFest, Ireland’s largest second-level STEM fair programme, now involves more than 16,000 students annually across over 165 fairs nationwide.
His journey to Phoenix required success at multiple levels of competition. Zack first emerged from regional SciFest competition, progressed through the national final against students from across Ireland, and ultimately secured one of the coveted Irish places at ISEF. At the SciFest National Final alone, only 51 students from 31 Regional Fairs qualified to compete.
Equally notable is the role of his mentor, science teacher, Ms Nolan who also mentored another first-place ISEF winner in 2024, making this success an exceptionally rare accomplishment in international STEM competition. Producing even a single category winner at ISEF is unusual; mentoring multiple first-place winners within such a short timeframe places her among a very small group of educators internationally to achieve that distinction.
Zack’s win is also a major moment for Irish STEM education. Competing against many of the world’s most advanced young researchers and programmers, 15-year-old Zack demonstrated that Irish students can excel on the biggest global stage for science and engineering innovation.
His success in Phoenix is likely to inspire a new generation of Irish students to pursue research, coding, engineering and scientific discovery — proving that age is no barrier to world-class achievement.
Huge congratulations from all of us Zack!
