Carl Sassenrath (born 1957 in California) is an architect of operating systems and computer languages. He brought multitasking to personal computers in 1985 with the creation of the Amiga Computer operating system kernel, and he is the designer of the REBOL computer language, REBOL/IOS collaboration environment, the Safeworlds AltME private messaging system, and other products. Carl is currently a Principal Engineer at Roku, Inc.