A person that hates everybody.
A sysadmin's skills are determined by his capacity to ignore time constraints and his attachment to bad faith. Additionally, a sysadmin usually believes anything with a higher level of abstraction than the C programming language is stupid.
Company: "Akshay, our email hasn't been working correctly for the past year. Can you please fix it?"
Sysadmin: "F*ck you! There is no way email is broken. I'll look at it tonight."