Leandro Marconi (1834–1919) was a Polish architect, active mainly in Warsaw. His father was Enrico Marconi, also a famed architect associated with that city, while his cousin was Leonard Marconi, a sculptor.
He was born Leandro Jan Ludwik Marconi on 23 April 1834 in Warsaw, then in Kingdom of Poland. His father Enrico Marconi was a noted architect, who moved to Poland in 1822 and settled in Warsaw, while his mother was Małgorzata (English: Margaret) née Heiton, a lady of Scottish descent.