Olaf Alfred Hoffstad (18 March 1865 – 15 September 1943) was a Norwegian botanist, writer, school principal and Conservative politician. Born in the mid-Norwegian town of Stjørdalshalsen to a mercantile family, he initially embarked on an educational career. Having taught at girls' schools across the country in the early 1890s, he was permanently employed at two universal schools in Sandefjord, a city whose political life he influenced in the latter part of his life.
During his schooldays Hoffstad read voraciously, developing a passion for botany that never left him. His first botanical book was published in 1891; it sold well, being released in nine revised editions before Hoffstad's decease during the Second World War. He also wrote floras intended for use in schools, the most prominent of which was published in six editions. In the 1890s Hoffstad travelled widely, searching for new plant species hitherto undiscovered.
In the conservative middle-class city of Sandefjord, Hoffstad engaged himself politically: in 1894 he was elected chairman of a local conservative youth league. Two years later, he entered the Sandefjord city council, which catapulted him into the political limelight: for 23 years he was the city's mayor, and later served as deputy representative for the Conservative Party in the Norwegian Parliament. A patriotic citizen of Sandefjord, Hoffstad was member of numerous boards of directors in the city.