Project:Administrators
Administrators (also known as sysops or admins) on MediaWiki.org are users with the technical capability to protect and delete pages, block users, and edit protected pages, among other things.
To become an admin, ask at Project:Requests. Information on the promotion process can be found there.
Lists of current admins, and current bureaucrats are available. To request a deletion, see Project:Deletion.
Stewards and global sysops should feel free to deal with vandalism and similarly routine and uncontroversial things, if necessary (Note: These are global groups defined by the CentralAuth extension and don't appear at Special:ListUsers, but at Special:GlobalUsers).