Oscar H. Ibarra (born September 29, 1941 in Negros Occidental, Philippines[1]) is a Filipino-American theoretical computer scientist, prominent for work in automata theory, formal languages, design and analysis of algorithms and computational complexity theory.

He is a Fellow of the Institute of Electrical and Electronics Engineers and the Association for Computing Machinery.

He was awarded the Blaise Pascal Medal[4] in Computer Science from EAS in 2007, and in 2008 he was elected a Foreign Member of Academia Europaea in the Informatics Section.

In 2008, he was awarded a Distinguished Visiting Fellowship from the UK Royal Academy of Engineering.

In July 2015, during the 40th anniversary celebration of the journal, Theoretical Computer Science, Ibarra was named the most prolific author in its 40-year history.