- Apr 4 Thomas Mayne Reid, Irish-American novelist (The Headless Horseman), born in Ballyroney, County Down, Ireland (d. 1883)
- Apr 5 Lewis Baldwin Parsons, American Brevet Major General (Union Army), born in Perry, New York (d. 1907)
- Apr 6 Francis Henry Brown, composer
- Apr 6 Aasmund Olavsson Vinje, Norwegian poet (d. 1870)
- Apr 8 Christian IX, King of Denmark (1863-1906), born in Gottorf Castle, Schleswig, Duchy of Schleswig (d. 1906)
- Apr 14 Marie of Saxe-Altenburg, Queen of Hanover, born in Hildburghausen, Saxe-Hildburghausen (d. 1907)
- Apr 20 Heinrich Göbel, German-born mechanic and inventor, born in Springe, Germany (d. 1893)
- Apr 22 Cadwallader Colden Washburn, American Major General (Union Army), born in Livermore, Maine (d. 1882)
- Apr 23 James Anthony Froude, English historian and novelist (The Nemesis of Faith), born in Dartington Rectory, Devon (d. 1894)
- Apr 23 John Gill Shorter, American politician (17th Governor of Alabama), born in Monticello, Georgia (d. 1872)
- Apr 25 Marek Konrad Sokolowski, Polish guitarist and composer, born in Zhytomyr, Ukraine (d. 1883)
Alexander II
Apr 29 Alexander II, Tsar of Russia (1855-81), born in the Moscow Kremlin in Russia (d. 1881)
Alexander II