this.Visible is not working in Windows Forms

It seems you can use the following:

private void Form1_Load(object sender, EventArgs e)
{
    this.Opacity = 0;
    this.ShowInTaskbar = false;
}

I just tested it in a winforms app and it worked.

(Also just found this: Single Form Hide on Startup)

I think it is not good idea to set visibility from form's Load event. Instead, I would do it by add a public method:

public void LoadForm(...)
{
   // do the all the initializations
}

and call the method to load the form. The form should be not visible unless you explicitly show it:

MyForm instance = new MyForm();
instance.LoadForm(...);
// instance.Show(); or ShowDialog() for dialog form not sure exactly the syntax.