Ole-Johan Dahl and Kristen Nygaard developed Simula (1962-1965) and Simula 67 (1967) while working at the Norwegian Computing Center (NCC) in Olslo Norway. These were the first two object-oriented programming languages.
Some articles1 also mention a Myrhaug as a co-worker. Simula was originally designed and implemented as a language for discrete event simulation, but was later expanded and re-implemented as a general purpose programming language.
"Note: Simula is not simply a "simulation-language": it has all of the capabilities of a general-purpose language plus support for simulation. Anecdotally, when someone once asserted that Simula was not a general-purpose language, Nygaard (one of the designers of Simula) countered by saying that Simula could do everthing that Fortran and Algol could, and more, so what would need to be removed before it could be called general-pupose!"2
1. Simula by Kathleen Fisher
The History of Simula and Simula 67
How Object-Oriented Programming Started by Ole-Johan Dahl and Kristen Nygaard, Department of Informatics, University of Oslo
Research Results: An Introduction to the Simula Programming Language
The History of Simula
Simula Research Laboratory - Honors to Simula Inventors
Alan M. Turing Award for Ole-Johan Dahl and Kristen Nygaard
Pascal Family Languages
Other Related Links