Successive Belgian kings:
It is also noteworthy that Belgium is the only current European monarchy that does not apply the tradition best described by the slogan "The king is dead, long live the king!". According to the Belgian constitution, the king only accedes to the throne when he takes a constitutional oath. For example, the present king didn't become monarch on the day on July 31, 1993 (the day his brother died) but on August 9 of that same year (when he took the constitutional oath). In all other current monarchies, the monarch becomes a monarch the moment his predecessor dies or abdicates.
Belgium has three official languages, of which Dutch and French are the most important. Many kings and members of the royal family are known under two names: a Dutch and a French one. For example, the current heir apparent is called Philippe in French and Filip in Dutch; the fifth King of the Belgians was Baudouin in French and Boudewijn in Dutch; the three kings who are known as Léopold in French are known to the Dutch speaking Belgians as Leopold (without accent).
In German, which is Belgium's third official language, kings are usually referred to under their French names. The same is true for English. The exception is Leopold, which is probably used this way, not because of the fact that it is used in Dutch, but because many Anglo-Saxon keyboards do not include an "é".
In Belgium, kings are always officially known with a ordinal, even when they are the first of their name. So King Baudouin was officially "King Baudouin I", even though there has not yet been a "King Baudouin II". But within Wikipedia one is expected to apply the Wikpedia naming conventions.
Other members of the Belgian Royal Family:Lists of incumbents