I spent time on due diligence and did not find this exact question, which surprised me greatly. I think it's a hugely important issue when it comes to Harry Potter. I see many questions posed with the presumption that Harry was a Horcrux -- but was he really? I'll give a couple of canon hints:
‘Well,’ said Slughorn, not looking at Riddle, but fiddling with the ribbon on top of his box of crystallised pineapple, ‘well, it can’t hurt to give you an overview, of course. Just so that you understand the term. A Horcrux is the word used for an object in which a person has concealed part of their soul.’
[...]
‘Encase? But how –?’
‘There is a spell, do not ask me, I don’t know!’ said Slughorn, shaking his head like an old elephant bothered by mosquitoes. ‘Do I look as though I have tried it – do I look like a killer?’
‘No, sir, of course not,’ said Riddle quickly.
Half-Blood Prince - pages 464 - 465 - Chapter twenty-three, Horcruxes
Was Harry an actual, legitimate Horcrux? Why or why not?
I'm looking only for a canon-based answer, so basically I'm willing to accept Word of God (J.K. Rowling), a direct quote from any of the ten Harry Potter books, or a definitive statement from Pottermore. Just as a general FYI, I am 100% disinterested in anything the HP Wikia has to say on the matter, and will likely skip over any answer with Wikia content. If this question is found to be a duplicate, by all means vote accordingly.