The Order of Merlin is an award bestowed upon wizards and
witches who have achieved great deeds. It has three different
levels: First Class, Second Class, and Third Class. The Order of
Merlin was founded by Merlin in the Middle Ages as an
organisation with the goal of promoting laws to protect and
benefit Muggles. It is unknown when the Order changed from an
organisation to an award or when its focus shifted from
advocating Muggle rights to honouring great wizarding
accomplishments in general. Order of Merlin, First ClassEdit -
Sirius Black's grandfather (either Arcturus Black III or Pollux
Black) - Albus Dumbledore - During the campaign to discredit
him, it was suggested by Remus Lupin that the Ministry would
consider taking away the Order of Merlin from Dumbledore.
Dumbledore claimed that he did not care as long as he is not
taken off the Chocolate Frog Cards. However, when Dumbledore's
credibility was restored, the Ministry's consideration to
retract the medal was cancelled. - Cornelius Fudge - Presumably