Molotow Blackliner Round Marker Pen
Like a Sharpie but more stylish and smaller. The Molotow Blackliner marker pen is the largest of the Blackliners (that I have used) for drawing.
The Blackliner round is a lightweight marker pen that is easy to control and draw with. It has a light, textured surface and good looking design cues.
This no-frills pen gets the job done if you're looking for sturdy, quick-drying, consistent ink that withstands heavy duty erasing (if you use an eraser on it, which I do.)