Friedrich Ladegast (August 30, 1818 – June 30, 1905) was a famous German organ builder.
Ladegast was born in Hochhermsdorf (now Hermsdorf), Saxony, to a carpenter and cabinet-maker.
He worked first for his brother Christlieb, an organ builder at Geringswalde, and built his first two organs at the age of twenty.
He went on to build over 200 organs, with notable works including the reconstruction of the organ of the Merseburg Cathedral (IV/81, 1855), and building the organ of the Nikolaikirche in Leipzig (IV/84,1859–62).
His largest instrument was for Schwerin Cathedral (IV/84, 1870–71).
His son, Oskar Ladegast, took over his firm in 1898.