Altadena is an unincorporated area and census-designated place located in Los Angeles County, California. It is situated within the San Gabriel Valley and Verdugos regions, positioned directly north of Pasadena and approximately 14 miles from Downtown Los Angeles.
As of the 2020 census, Altadena had a population of 42,846, representing a slight increase from its 2010 figure. In early 2025, the community experienced severe impacts resulting from the Eaton Fire.