Автор: http://www.lmc-mediaagentur.de

procedure TForm1.FormCreate(Sender: TObject);
begin
  {This only works for classes registered using RegisterClass}
  RegisterClasses([TButton, TForm]);
end;

procedure TForm1.Button1Click(Sender: TObject);
var
  CRef: TPersistentClass;
  PTI: PTypeInfo;
  AControl: TControl;
begin
  CRef := GetClass('TButton');
  if CRef <> nil then
  begin
    AControl := TControl(TControlClass(CRef).Create(Self));
    with AControl do
    begin
      Parent := Self;
      Width := 50;
      Height := 30;
    end;
    Inc(Id);
  end
  else
    MessageDlg('No such class', mtWarning, [mbOk], 0);
end;