Charles Alexander (Karl Alexander August Johann; 24 June 1818 – 5 January 1901) was born in Weimar, Karl Alexander was the second but eldest surviving son of Karl Frederick, Grand Duke of Saxe-Weimar-Eisenach and Grand Duchess Maria Pavlovna of Russia. His mother engaged as tutor for Karl the Swiss scholar Frédéric Soret who became a close acquaintance to Johann Wolfgang von Goethe.
When he was the Hereditary Grand Duke, Karl Alexander established a strong friendship with Fanny Lewald and Hans Christian Andersen, but this close relationship stopped in 1849 for the war against Denmark over the duchies of Schleswig-Holstein (the First Schleswig War). On 8 July 1853 his father died, and Karl Alexander became Grand Duke; however, he postponed his constitutional accession until Goethe's birthday, on 28 August 1853.
Karl Alexander renovated Wartburg Castle and left his traces in many places in Eisenach. He was the protector of Richard Wagner and Franz Liszt, retained the tradition of Weimar's classical period, and gave the old part of Weimar a new and better appearance with the establishment of the Herder monument and the double monument for Goethe and Schiller. In 1860, he founded the Grand-Ducal Saxon Art School in Weimar (with Arnold Böcklin, Franz von Lenbach, and the plastic artist Reinhold Begas). As Grand Duke he was automatically rector, or president, of the University of Jena, where he supported especially the collections, among them prominently the Oriental Coin Cabinet.
In the Franco-Prussian War (1870–1871), Karl Alexander participated only in "Samaritan"; he stressed, however, for his entrance into the war in favor of Schleswig in 1849. The Weimar Congress of the Goethe Federation (opposing the Lex Heinze) occurred towards the end of his reign, in November 1900. That congress described his government as the Silver Age of Weimar.
In late December 1900, Karl Alexander reportedly fell ill with influenza. His condition soon worsened, becoming complicated with inflammation of the lungs and a slowing heart rate before the end of the month.[4][5] He died at Weimar on 5 January 1901. Following his death, he was succeeded as Grand Duke by his grandson Wilhelm Ernst, his only son Carl August having predeceased him.