1803 in Germany

Holy Roman Empire

• Francis II (5 July 1792 – 6 August 1806)

Important Electors

• Baden- Charles Frederick (27 April 1803 – 6 August 1806)
• Bavaria- Maximilian I (16 February 1799 – 6 August 1806)^[1]
• Saxony- Frederick Augustus I (17 December 1763 – 20 December 1806)^[2]
• Württemberg - Frederick I (1803 – 30 October 1816)^[3]

Kingdoms

• Kingdom of Prussia
  • Monarch – Frederick William III of Prussia (16 November 1797 – 7 June 1840)^[4]

Grand Duchies

• Grand Duke of Mecklenburg-Schwerin
  • Frederick Francis I (24 April 1785 – 1 February 1837)^[5]
• Grand Duke of Mecklenburg-Strelitz
  • Charles II (2 June 1794 – 6 November 1816)^[6]
• Grand Duke of Oldenburg
  • Wilhelm (6 July 1785 – 2 July 1823) Due to mental illness, Wilhelm was duke in name only, with his cousin Peter, Prince-Bishop of Lübeck, acting as regent throughout his entire reign.^[7]
  • Peter I (2 July 1823 – 21 May 1829)^[7]
• Grand Duke of Saxe-Weimar
  • Karl August (1758–1809) Raised to grand duchy in 1809

Principalities

• Schaumburg-Lippe
  • George William (13 February 1787 – 1860)
• Schwarzburg-Rudolstadt
  • Louis Frederick II (13 April 1793 – 28 April 1807)^[8]
• Schwarzburg-Sondershausen
  • Günther Friedrich Karl I (14 October 1794 – 19 August 1835)
• Principality of Lippe
  • Leopold II (5 November 1802 – 1 January 1851)^[9]
• Principality of Reuss-Greiz
  • Heinrich XIII (28 June 1800 – 29 January 1817)
• Waldeck and Pyrmont
  • Friedrich Karl August (29 August 1763 – 24 September 1812)

Duchies

• Duke of Anhalt-Dessau
  • Leopold III (16 December 1751 – 9 August 1817)^[10]
• Duke of Saxe-Altenburg
  • Duke of Saxe-Hildburghausen (1780–1826) - Frederick^[5]
• Duke of Saxe-Coburg-Saalfeld
  • Francis (8 September 1800 – 9 December 1806)
• Duke of Saxe-Meiningen
  • Bernhard II (24 December 1803 – 20 September 1866)^[11]
• Duke of Schleswig-Holstein-Sonderburg-Beck
  • Frederick Charles Louis (24 February 1775 – 25 March 1816)^[12]

Other

• Landgrave of Hesse-Darmstadt
  • Louis I (6 April 1790 – 14 August 1806)^[5]

• 25 February – A major redistribution of territorial sovereignty within the Holy Roman Empire is enacted via an act known as the Reichsdeputationshauptschluss.
• 30 May – Following Britain's declaration of war on France, Édouard Mortier leads 12,000 troops in an Invasion of Hanover
• 5 July – The convention of Artlenburg confirms the French occupation of Hanover (which had been ruled by the British king).

January–June

• 15 February
  • John Sutter, pioneer (died 1880)^[13]
  • Karl Friedrich Schimper, botanist, naturalist and poet (died 1867)^[14]
• 26 February – Arnold Adolph Berthold, physiologist and zoologist (died 1861)^[15]
• 17 March Carl Jacob Löwig, chemist (died 1890)^[16]
• 12 May – Justus von Liebig, chemist (died 1873)^[17]

July–December

• 8 July – Julius Mosen, poet (died 1867)
• 17 July – Johann Samuel Eduard d'Alton, anatomist (died 1854)
• 19 July – Wolfgang Franz von Kobell, mineralogist and writer (died 1882)
• 5 October – Friedrich Bernhard Westphal, painter (died 1844)
• 29 November – Gottfried Semper, architect (died 1879)
• 26 September – Adrian Ludwig Richter, German painter (died 1884)
• 6 October – Heinrich Wilhelm Dove, German physicist and meteorologist (died 1879)
• 31 December – Johann Carl Fuhlrott, German paleoanthropologist (died 1877)

January–June

• 18 February – Johann Wilhelm Ludwig Gleim, poet (born 1719)
• 14 March – Friedrich Gottlieb Klopstock, poet (born 1724)

July–December

• 18 December – Johann Gottfried Herder, philosopher and writer (born 1744)