Lothar Bucher (25 October 1817 – 12 October 1892) was a German publicist and trusted aide of German chancellor Otto von Bismarck.
Bucher was born in Neustettin, Pomerania, his father being master at a gymnasium. After studying at the University of Berlin he adopted the legal profession. Elected a member of the National Assembly in Berlin in 1848, he was an active leader against the democratic party. With others of his colleagues he was in 1850 brought to trial for having taken part in organizing a movement for refusal to pay taxes; he was condemned to fifteen months imprisonment in a fortress, but left the country before the sentence was executed.