doorkeeper

from The American Heritage® Dictionary of the English Language, 5th Edition.

• noun One who is employed to guard an entrance or gateway.

from The Century Dictionary.

• noun One who guards the door or entrance of a house or an apartment, and admits persons entitled to admittance; a janitor.
• noun In the early church and in the Roman Catholic Church, same as ostiary.

from the GNU version of the Collaborative International Dictionary of English.

• noun One who guards the entrance of a house or apartment; a porter; a janitor.

from Wiktionary, Creative Commons Attribution/Share-Alike License.

• noun The person in charge of an entryway, sometimes just a doorman, sometimes something more.

from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.

• noun someone who guards an entrance
• noun an official stationed at the entrance of a courtroom or legislative chamber
• noun the lowest of the minor Holy Orders in the unreformed Western Church but now suppressed by the Roman Catholic Church