After the Giles gifset I made some time ago (before the cruel and painful death of my poor poor laptop), I thought about all kinds of characters that remind me of Athos.
The eldest among his friends, not just by years, but by spirit. Smart like hell, but never showing it unless he asked. Brave, but always cold headed. A man with that quiet power about him that makes the others look up to him. And, of course, has a dark and painful past that reflects all his life.
So there are some characters that remind me of that special man. Not all of them have all of the things above in them, but they have similarities.
Rupert Giles (Buffy the Vampire Slayer)
Remus Lupin (Harry Potter)
Sazed (Mistborn trilogy)
Leo Mc'Garry (West Wing)
Aragorn (Lord of the Rings)
Eddard Stark (ASOIAF)
Bobby Singer (SPN)
What do you think? Have some more ideas?