How to counter Nocturne
Let us take a look on how to beat Nocturne. We will look at champions who are strong against Nocturne and who are weak against Nocturne. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Jungle champion who counters Nocturne. You can already win in champion select with the right counters for Nocturne. If you want to know how to counter Nocturne then you need to take into account the best picks vs Nocturne and the worst picks vs Nocturne. This Nocturne counter data is based on matches played by Pros on patch 14.9 and previous ones. It is important to see whether Pros counter picked Nocturne or whether they played as Nocturne.
Champions used by Pros to counter pick Nocturne
Looking at the matches from Pros (see table Pros counter picked Nocturne) we can see that they picked 
Lee Sin most often to counter pick Nocturne. The matchup Lee Sin vs Nocturne occured 18 times. Nocturne has 13 wins and 5 losses in this matchup. Learn how to counter pick Lee Sin to get another perspective on the data.
Lane outcome for Nocturne
When looking at Nocturne counters you will notice that win rates alone are not conclusional. Therefore we provide an overview (see table Lane Outcome) where you can see the lane outcome of Pros who played Nocturne. The lane outcome of Nocturne consists of three outcomes: Win, Loss or Draw. Let's take a look of Nocturne lane and match outcome for specific matchups. Considering the lane outcome and the match outcome of a specific matchup, might enable you to find the right counter for Nocturne.
Conclusion
Analyze the available data and learn how to beat Nocturne. To master Nocturne take also a look on Nocturne builds and runes for Nocturne. Good luck, Summoner!