Henry Massalin is an American computer scientist and programmer. She pioneered the concept of superoptimization,and designed the Synthesis kernel, a small kernel with a Unix compatibility layer that makes heavy use of self-modifying code for efficiency.Massalin's first breakthrough product came while studying at Columbia. Massalin developed Synthesis, an operating system kernel that allocated resources, ran security and low-level hardware interfaces, and created executable code to improve performance.