Probably one of the most influential Altadenans ever was Jon Postel, who was born on this day in 1943 (he died in 1998). Postel was one of the "fathers of the Internet," inventing and administering its address system for 30 years, and coming up with the current administration system where addresses are managed by several non-governmental organizations.
He was born in Altadena and raised and educated in Southern California.