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;