This is a tough questions. First of all because I don't know all the talented makeup artists on this world, I maybe know 0.001% of them.
Secondly because picking one is very difficult when they all have such different styles.
If I consider their very different work, I'd have to mention two very different makeup artists: Alex Box and Lisa Eldridge.
Lisa Eldridge has created so many beautiful looks for magazine cover, I do consider her a reference in the world of glamour and beauty makeup.
I think we are incredibly lucky that she's willing to share her experience and talent through her makeup tutorial videos, which not every artist is open to doing!
Alex Box is a totally different story. We're not in the field of the glamourous wearable makeup here, it's all about abstract art.
And when Alex Box creates a look that is more on the 'realistic' side, like she does for Illamasqua, then these are always looks that make a scene. Why be scared, since makeup washes off?
So yes, those two, for very different reasons.
Still, I feel the need to mention François Nars for his healthy and interesting vision about makeup and beauty.