What does the title "Professor of the Graduate School at the History Department" represent? Does it represent the dean/head of a department?

This is a title I found on the website of a certain top 20 US university. I searched for the title 'dean' at the department but was unlucky. I found instead "Professor of the Graduate School".

HELP!

you could try asking them, by phone or email. I have no idea, but it does say of the graduate school, so does this mean the title only applies to postgrad study??? hmmmm. I'd ask them if I were you.