Lars Eliel Sonck (born in Kälviä, Finland 1870; died in Helsinki, Finland 1956) was a Finnish architect. He graduated from Helsinki Polytechnic Institute in 1894 and immediately won a major design competition for a church in Turku, ahead of many established architects.
Sonck ignored the growing trend toward architectural rationalism. Instead, he borrowed from the historical tradition of Finland's medieval stone structures and residential wood based architecture. His more monumental commissions show the influence of a neo-Romanesque style.
A prominent figure in Finland's search for architectural identity, Sonck played a leading role in the development of a National Romanticism.
Sonck designed for Jean Sibelius and his wife their home, now a museum, called "Ainola".