Columnist
A noun for a person from the noun 'column' is columnist, a person who writes a newspaper column.
A columnist...?
Carolyn Hax writes a column on relationship advice, initially at Washington Post, but now syndicated at over 200 papers and magazines. Her column is also available on ereaders.
Columnist.
In my opinion Qalandar awan is a column writer in different dailies of Pakistan. He also writes on some web papers as well.I could read some of his columns at different places.
nfernelson
A jogger could be a blogger who writes a running column.
Writes a Wedding column
The person who makes a will (or 'testament') is a testator.
A composer is a person who writes music.
A person who writes laws is called a legislator or a lawmaker.