Автор: http://www.swissdelphicenter.ch

// When you create a file or directory, you become the owner of it.
// With GetFileOwner you get the owner of a file.

function GetFileOwner(FileName: string;
  var Domain, Username: string): Boolean;
var
  SecDescr: PSecurityDescriptor;
  SizeNeeded, SizeNeeded2: DWORD;
  OwnerSID: PSID;
  OwnerDefault: BOOL;
  OwnerName, DomainName: PChar;
  OwnerType: SID_NAME_USE;
begin
  GetFileOwner := False;
  GetMem(SecDescr, 1024);
  GetMem(OwnerSID, SizeOf(PSID));
  GetMem(OwnerName, 1024);
  GetMem(DomainName, 1024);
  try
    if not GetFileSecurity(PChar(FileName),
      OWNER_SECURITY_INFORMATION,
      SecDescr, 1024, SizeNeeded) then
      Exit;
    if not GetSecurityDescriptorOwner(SecDescr,
      OwnerSID, OwnerDefault) then
      Exit;
    SizeNeeded := 1024;
    SizeNeeded2 := 1024;
    if not LookupAccountSID(nil, OwnerSID, OwnerName,
      SizeNeeded, DomainName, SizeNeeded2, OwnerType) then
      Exit;
    Domain := DomainName;
    Username := OwnerName;
  finally
    FreeMem(SecDescr);
    FreeMem(OwnerName);
    FreeMem(DomainName);
  end;
  GetFileOwner := True;
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  Domain, Username: string;
begin
  GetFileOwner('YourFile.xyz', domain, username);
  ShowMessage(username + '@' + domain);
end;

// Note: Only works unter NT.