Ferdinand I (26 February 1861 – 10 September 1948), born
Ferdinand Maximilian Karl Leopold Maria of Saxe-Coburg and Gotha, was the ruler of
Bulgaria from 1887 to 1918, first as
knyaz (
prince regnant, 1887–1908) and later as
tsar (king, 1908–1918). He was also an author,
botanist,
entomologist and
philatelist.