What is the biggest killer of men?

Heart disease is the leading cause of death in men each year. Men are more likely than women to die from most of these causes.

https://dph.illinois.gov/topics-services/life-stages-populations/mens-health/top-10-causes-death.html#:~:text=Heart%20disease%20is%20the%20leading,from%20most%20of%20these%20causes.