Which Russian tsar was one of Queen Victoria's godparents?

Alexander I was one of Queen Victoria’s godparents.

Victoria was privately christened on 24 June 1819 in the Cupola Room at Kensington Palace. Her godparents included Tsar Alexander I of Russia, her uncle George, Prince Regent, Queen Charlotte of Württemberg, and her maternal grandmother, the Dowager Duchess of Saxe-Coburg-Saalfeld. Several godparents were represented by proxies at the ceremony.

Alexander’s connection also helps explain Victoria’s first baptismal name, Alexandrina. She was named partly in his honour, although she later preferred Victoria. The Russian ruler is easy to confuse with Alexander II, who became tsar only in 1855, decades after Victoria’s baptism. Nicholas I was also a contemporary Russian emperor, but he was not one of Victoria’s godparents.