Carl Alvar Wirtanen (1910 – 1990) was an American astronomer who worked at Lick Observatory.

He discovered periodic comet 46P/Wirtanen, as well as eight asteroids, including notably the Apollo asteroid (29075) 1950 DA, which is considered to have a non_negligible risk of impacting the earth in the year 2880. He also discovered two other Apollo asteroids: 1685 Toro and 1863 Antinous.