First NCLT Coin

Early Maundy Money was intended to circulate. It was originally the whole point of the Maundy ceremony: giving money away to poor people. The coins given to those poor people were intended to be spent by them.

The answer to your question does depend on what criteria you're going to use to determine that something is "NCLT". Many coins down through history have been made, as Maundy coins were made, specifically to be given away as gifts; one can think of the "Liberalitas" (generosity) coins of certain Roman emperors, which were specifically made so that the emperor could throw them into the crowds on festive occasions. But again, the point was you then went and spent your gift.

One of the key components to "modern" NCLT is that it costs more than its face value to buy from the mint; the main thing preventing "NCLT" from becoming "CLT" is that whoever bought it would lose money on the deal if they simply spent it. If "paying above face value" is an essential criteria (and personally I think it is, since any coin issued for face value will tend to circulate for that face value, whether the issuing government intends for this to happen or not), then one has to go back and try to find early examples of coins being sold for a premium above face value.

You won't find examples of that in ancient times, not in the West anyway, since to have NCLT you need a population of coin collectors to buy the things and, with the exception of a few eccentric kings and emperors, coin collecting in anything remotely resembling the modern sense simply didn't exist prior to the Renaissance. You certainly don't have the concept of mints selling coins for a premium above face value until well into the modern era.

Coin collecting grew in popularity in Germany from around the sixteenth century, especially among the minor princes and nobles. Many of them had been granted hereditary coinage-issuing rights by the Holy Roman Emperor but ruled territories so tiny that they had no real need to issue circulating coinage and had no coin-minting facilities of their own, so they exercised their "coinage rights" by commissioning the striking of overly elaborate and gigantic thalers and multiple-thalers from nearby mint-cities, and then selling the coins (usually for a tidy profit) to their coin-collecting neighbours.

These coins certainly were not intended for circulation, within the tiny territories named on the coin or anywhere else, and judging by their typical condition most of them never actually saw use as money. They also qualify as "legal tender" in that the princes certainly had every right to issue whatever coins they pleased, just as governments do today. So I would say they, collectively, qualify as the "earliest NCLT".

Well, there's kind of a distinction between NCLT versus NIFC. Some coins are definitely the latter but not the former (most proofs, modern half dollars, British 5-pound coins, and so on).
I'd say the first NIFC coins were some of the Greek dekadrachms, though it is not impossible that other ones appeared even earlier; as for NCLT, Sap's answer appears to be correct to the best of my knowledge (it's probably impossible to say specifically).

Um, $1 coins in the US do circulate, even the latest issues that are pretty definitely not intended to.
There are many cases historically of denominations that were not issued much because they were just that unpopular - stuff like 20 cent pieces in the US, or double florins in Britain - and, at least until very recently, none of them were NCLT, or even NIFC (yes, even the $3 golds were not either).
First coins to be issued despite their ridiculous unpopularity were probably some of the Wang Mang series (early 1st century AD in China); they also resemble NCLT in other ways, actually.

OTOH, nearly all US classic commemoratives were issued at above issue price; I highly doubt it really makes them NCLT.

Um, yes it does. I'd regard all "classic" American commemoratives as NCLT. Same as the only equivalent in the Australian series, the 1934/5 florin.


I did consider contorniates. But their uncertain origin and purpose makes it impossible to classify them with any certainty as either "non-circulating" (Were they used as money? Who can tell?) or "legal tender" (Did the government issue them? Were they assigned an official value?), so on that basis I excluded them.

Large numbers of some of the classic US commemorative issues were placed into circulation by either their sponsor, banks or the US Treasury. They circulated alongside regular-issue coins and did not cost anyone more than their face value to collect by those who found them. Granted, not all issues had volumes of coins dumped into circulation, but it happened enough to make me hesitant to call all coins of the series "NCLT." NIFC might be the better classification if you want to apply one to the entire series.