How to counter Aatrox
Let us take a look on how to beat Aatrox. We will look at champions who are strong against Aatrox and who are weak against Aatrox. Use win rate, gold difference and creep score difference at minute 10 to find the best 
Top champion who counters Aatrox. You can already win in champion select with the right counters for Aatrox. If you want to know how to counter Aatrox then you need to take into account the best picks vs Aatrox and the worst picks vs Aatrox. This Aatrox counter data is based on matches played by Pros on patch 14.22 and previous ones. It is important to see whether Pros counter picked Aatrox or whether they played as Aatrox.
Champions used by Pros to counter pick Aatrox
Looking at the matches from Pros (see table Pros counter picked Aatrox) we can see that they picked 
Gnar most often to counter pick Aatrox. The matchup Gnar vs Aatrox occured 36 times. Aatrox has 21 wins and 15 losses in this matchup. Learn how to counter pick Gnar to get another perspective on the data.
Lane outcome for Aatrox
When looking at Aatrox 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 Aatrox. The lane outcome of Aatrox consists of three outcomes: Win, Loss or Draw. Let's take a look of Aatrox 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 Aatrox.
Conclusion
Analyze the available data and learn how to beat Aatrox. To master Aatrox take also a look on Aatrox builds and runes for Aatrox. Good luck, Summoner!