Dennis MacAlistair Ritchie (username: dmr, born September 9, 1941) is an American computer scientist notable for his influence on C and other programming languages, and on operating systems such as Multics and Unix. He received the Turing Award in 1983 and the National Medal of Technology 1998 on April 21, 1999. Ritchie was the head of Lucent Technologies System Software Research Department when he retired in 2007.