I think I've finally fully mourned the loss of the 'Marathon' name to the clearly inferior 'Snickers' - bring 'em back at the size Marathons bars were, that'd be a thing!
In the US, the Marathon branding was used for a 12” long caramel braid covered in chocolate. The marketing was that it was so big, it would take a long time and a lot of effort to finish (like running a marathon). If I recall correctly, the packaging even had a ruler printed on the back of the wrapper.