Kostis Sagonas is an academic who is working in the area of programming languages and systems. He has been heavily involved in the development of Erlang and its implementation since 1999. At Uppsala University, he has led the development team of the HiPE native code compiler that nowadays is part of Erlang/OTP. Together with his students, first at Uppsala University in Sweden and more recently at the National Technical University of Athens in Greece, he has proposed various changes and additions to the Erlang language (most notably, algorithms for binary pattern matching, the extension for bit-level pattern matching and bit-stream comprehensions, and the language of type and spec declarations), and has contributed to its compiler and runtime system. Besides HiPE, he has designed and implemented many software development tools for Erlang (Dialyzer, Typer, Tidier, PropEr, Concuerror, ...) and has contributed bug fixes to many open-source Erlang projects.