It's interesting really to wonder, just how many times from start to finish on the series, did Merlin actually save Arthur's life and how many times on the reverse?
How many times did Arthur save Merlin's life?
One final question for this, is how many times was Arthur's life in danger all together that someone, needed to save him. (Bonus if you can also tell me how many times he himself saved his own life from a close call)
Merlin saved Arthur anywhere between 30-39 times depending on which ones you want to count. Some people made youtube videos of every time Merlin acted as a guardian. Here is a pretty cool edit: https://www.youtube.com/watch?v=IFhK2kbMeZk.