Sami Erol Gelenbe (born 22 August 1945) is a Turkish-French computer scientist, electronic engineer and applied mathematician who is professor in in the Institute of Theoretical & Applied Informatics, Polish Academy of Sciences (IITIS-PAN) since 2017. Holding a PhD from the Polytechnic Institute of New York University (1970), He has been habilitated for Doctoral Supervision in Poland (Dr Habil) in 2023, and was previously habilitated for Doctoral Supervision in France (Docteur es SCiences Mathematiques, University of Paris VI) in 1973. His previous full professorships include the University of Liege, Belgium (1974-79), University of Paris-Saclay (1979-1986), University of Paris V (1986-1994), Duke University, USA (1993-1998), University of Central Florida (1998-2003), and Imperial College (2004-2020). Known for pioneering the field of modelling and performance evaluation of computer systems and networks throughout Europe, he invented the random neural network and the eponymous G-networks. His many awards include the ACM SIGMETRICS Life-Time Achievement Award, and the in Memoriam Dennis Gabor Award of the Hungarian Academy of Sciences.

He graduated from Ankara Koleji in 1962 and the Middle East Technical University in 1966, winning the K.K. Clarke Research Award for work on “partial flux switching magnetic memory systems”. Awarded a Fulbright Fellowship, he continued his studies at Polytechnic University, where he completed a master's degree and a PhD thesis on “Stochastic automata with structural restrictions”, under the supervision of Edward J. Smith. After graduation he joined the University of Michigan as an assistant professor. In 1972, and then on leave from Michigan, he founded the Modeling and Performance Evaluation of Computer Systems research group at INRIA (France), and was a visiting lecturer at the University of Paris 13 University. In 1971 he was elected to the second chair in Computer Science at the University of Liège, where he joined Professor Danny Ribbens in 1973, while remaining a research director at INRIA. In 1973, he was awarded a Doctorat d'État ès Sciences Mathématiques from the Paris VI University with a thesis on "Modèlisation des systèmes informatiques", under Jacques-Louis Lions.

Notable contributions: Gelenbe has contributed pioneering research concerning the performance of multiprogramming computer systems, virtual memory management, data base reliability optimisation, distributed systems and network protocols. He formed, led, and trained the team that designed the commercial QNAP Computer and Network Performance Modeling Tool. He introduced the Flexsim Object Oriented approach for the simulation in manufacturing systems. He carried out some of the first work on adaptive control of computer systems, and published seminal papers on the performance optimisation of computer network protocols and on the use of diffusion approximations for network performance. He developed new product form queueing networks with negative customers and triggers known as G-networks. He also introduced a new spiked stochastic neural network model known as the random neural network, developed its mathematical solution and learning algorithms, and applied it to both engineering and biological problems. His inventions include the design of the first random access fibre-optics local area network, a patented admission control technique for ATM networks, a neural network based anomaly detector for brain magnetic resonance scans, and the cognitive packet network routing protocol to offer quality of service to users. From 1984 to 1986 he served as the Science and Technology Advisor to the French Secretary of State for Universities. He founded the ISCIS (International Symposium on Computer and Information Sciences) series of conferences that since 1986 are held annually in Turkey, the USA and Europe to bring together Turkish computer scientists with their international counterparts. According to the Mathematics Genealogy project, Gelenbe has graduated over 90 PhD students, placing him in the Top 25 worldwide – all time – PhD supervisors in the mathematical sciences. https://www.mathgenealogy.org/id.php?id=103790