Lotz Károly Antal Pál, or Karl Anton Paul Lotz (16 December 1833 – 13 October 1904) was a German-Hungarian painter.
Karl Lotz was born in Bad Homburg vor der Höhe, Germany, the 7th and youngest surviving child of Wilhelm Christian Lotz and Antonia Höfflick (Höfflich). His father was a valet of Prince Gustav zu Hessen-Homburg at the time when the prince was representing Austria at the Congress of Vienna, which among other matters dealt with the House of Hessen-Homburg's rights of sovereignty over Hessen-Darmstadt. The sudden death of the young Baron von Sinclair, chargé d'affaires, forced W. C. Lotz temporarily into the rôle. While in Hungary in 1815 he made the acquaintance of the 13-year-old Antonie Hoefflich, whom he married three years later. She gave birth to 8 children, of whom Karl was the youngest.
W. C. Lotz died in 1837 and Antonie moved the family to Pest (now one of the three constituent parts of Budapest; the one on the east bank of the River Danube). Karl attended the Piaristengymnasium, where, although Calvinist, he was awarded a scholarship for his exceptional academic performance. He began his artistic career as a pupil of the Hofkapellmeister Destouches, then in the academy of the Venetian master Jakab Marastoni (1804-1860). Later he was a pupil of the historical painters Henrik Weber (1818-1866) in Budapest and Carl Rahl (1812-1865) in Vienna.
Together with Rahl he worked on numerous commissions. Later he started on his own original works, first as a romantic landscape artist in scenes of the Alföld (the Hungarian lowland plain), and then as a creator of monumental murals and frescos in the style of the Venetian master Tiepolo.