I picked up a couple of these (since my International Note 4 came with a Euro charger) and have had no problems with them, they work exactly like the original the phone came with. If they're not "authentic" then they're just as good and it doesn't matter :) they don't overheat and the phone doesn't reject them in any way. I also use the same chargers to power my Nexus 7 (2013, not fast charging, of course) and iPhone 6 without issue.

Probably real.

Samsung sells real fast chargers on Amazon for $10 a piece.

Link for those interested

Second edit: If you read the reviews on Amazon you will see a bunch of negative ones. Make sure you buy the part from Samsung's profile. There are other sellers who are selling knockoffs.

3 edit: I am either blind or something changed in that link. It is no longer through samsung directly, but it is still fulfilled by Amazon. If you buy it and it doesn't work they are really liberal with their return policy.

Is this not the REAL Samsung charger?? $11 http://www.amazon.com/Samsung-Travel-Charger-Galaxy-Note/dp/B00WXIIQ1C/ref=sr_1_3?ie=UTF8&qid=1446752489&sr=8-3&keywords=samsung+quick+charger

Specifically this one

Or this one, since it's cheaper

Samsung Travel Charger for Galaxy Note 4/Edge S6 - Non-Retail Packaging - White https://www.amazon.com/dp/B00WXIIQ1C/ref=cm_sw_r_awd_AxF5vb2SS9V1Q

Sorry for the dirty link, I'm on mobile but I bought 2 of these. It has fast charge and works great.