The Clan Fraser stone at the historic battlefield has become a key stop off by fans of the book and spin-off television series, many on Outlander-themed tours, who are keen to tick off Highland landmarks with links to story.
Clan Fraser is one of the key families in the Outlander story, with lead character Jamie Fraser fighting for the Jacobites at Culloden.
Now, the grave marker, which marks real grave pits dug deep beneath the battlefield, has been cordoned off as the ground becomes eroded, raising concerns about how heritage sites linked to Outlander are conserved amid rising visitor numbers.
Last year, owners National Trust for Scotland sought scheduled monument consent to repair the ground given similar problems. It now appears that these works have not been adequate to deal with the problem, with talks ongoing with Historic Environment Scotland to find a suitable solution.
Raoul Curtis-Machin, National Trust for Scotland’s Operations Manager at Culloden said: "The area around the grave markers had been suffering wear and tear because visitors had been walking off the main footpath to take a closer look at the stones.
"Worst hit recently is the area around the Fraser Stone, which has become a site of pilgrimage for Outlander fans.
"Last year this was not really an issue because the ground stayed hard in the dry weather, but this year it has become very muddy with the heavy rain. Visitors still have full access to the whole area – we have just cordoned off the worst patch immediately in front of the Fraser Stone.
“We will be topdressing and re-seeding the area in the meantime, according to the Scheduled Ancient Monument consent which has been granted, and we are exploring other solutions with Historic Environment Scotland.”
Last year, a 28 per cent increase in visitor numbers was recorded at the Culloden visitor centre with the 'Outlander effect' said to be driving the rise.
VisitScotland is currently analysing how much the Outlander series, which charts the romance of a Highland clansman and his English wife during the 18th Century in Scotland and North America, is worth to the Scottish economy given its huge popularity, particularly amongst the American market.
While it drives huge numbers of visitors to the Highlands and other sites used as locations in the story, concerns have been raised about the impact on historic sites.
Andrew McKenzie, a former manager at Culloden Battlefield who now runs Highland Historian Heritage Consultancy and Bespoke Tour Guiding, said that conservation had to be key amid rising visitor numbers.
He said he had watched the area around the Clan Fraser grave marker become damaged over the last five years with some visitors to the battlefield only now going to this part of the site.
Mr McKenzie said: "If you look at the area around the grave, the damage has really ramped up in the last five years or so.
"Often when I am doing tours of the battlefield, you see big groups of people going through the car park, standing round the stone and then leaving things on top of it, which in itself is not great, and then disappearing off the site directly back onto the bus.
"That is a new thing that seems to be developing and it is unfortunate for all parties involved, including NTS. You would hope the visitor would go into the centre and spend a bit more time there.
"It is so clear that this is a continuing thing and that it is going to get worse."
He said visitor should be more away that they are visiting the site of 'real graves and real bodies' and not just an Outlander location.
Mr McKenzie said: "We don't know who is in each grave but, despite this being a pilgrimage site for Outlander fans, I would respect people to respect the dead who lie in this area and realise that it is not just part of the Outlander story.
"We are at a point now where visitor numbers are getting so big.
"I just really hope and really encourage organisations such as NTS, Historic Environment Scotland and Visit Scotland to always remember conservation within that and to attempt to find a balance."