Queen Wilhelmina of the Netherlands reigned from 1890 to 1948, before abdicating in favor of her daughter, Queen Juliana who then reigned until 1980 when she abdicated in favor of her daughter, Queen Beatrix of the Netherlands. Beatrix followed suit and abdicated in 2013 in favor of her son and heir apparent, King Willem-Alexander.
Abolition of monarchy
King Louis XVI of France reigned from 1774 until the overthrow of the monarchy in 1792 and his execution the following year.
Emperor Haile Selassie of Ethiopia reigned for over 40 years (1930-1974) until the Derg forced him to abdicate and abolished the 3,000 year old monarchy, making him the 225th and final Emperor of Ethiopia.