While most events have some uninvited guests – none are usually as creepy as this.
As guests were filing into Westminster Abbey a creepy-looking shadow passed over the doors to the ancient building.
Video footage shows a dark figure with a hooded cloak, holding a long rod – that looks eerily close to the long scythe the reaper carries – quickly dashing across the entrance.
In just a few seconds the shadow flitted across the door and was gone again.
The exact moment was captured by Twitter user @realjoegreeeen who took to the social media platform to reveal his shock.
He tweeted: ‘Anyone else just notice the Grim Reaper at Westminster Abbey #Coronation’
The video has since been seen almost half a million times – with other viewers tweeting about the sighting.
One person wrote: ‘the grim reaper has appeared’
‘It’s like that scene in Exorcist 3’ tweeted another.
‘Is that for real?’ questioned another.
And noticing something else, another added: ‘I’ve seen this clip a few times now and can’t get over the musical accompaniment of the reaper’s appearance.’
Today’s events mark the first coronation since 1953 when the late Queen Elizabeth was crowned at Westminster Abbey and went on to reign for more than 70 years.
King Charles ascended the throne in September last year when his mother died, and today officially took the crown.
More than 100 million people watched on from home all over the world, as King Charles and Queen Camilla took part in the historic day.