So, what's so special about his name? Simple. In MH he is called "The Operator" if we take that as a starting point and we take MH as a true story then this name can suggest us a few things:
When you think of the word "Operator" you ether think of a lady answering the phone to put you in touch with someone or about anything at all that executes the task assigned. If the first one is correct then we just have to think about it in another way. If it's name was picked from the phone operator then he takes those that ether contact or want to be contacted, but this is very likely not the case since his victims dissapear.
If the second one is correct then... ether Slender has a set goal or was sent by someone.
This is as far my speculation goes. Next I will write about my speculations about what slender may be so you can expect a long blog entry.
I'm open to feedback, sugestions and correction if any were needed so please feel free to coment :)