Sometimes you might want to add your own Gizmo icon to your objects. I will tell you how to do it.
First you should have an folder in your Assets folder called Gizmos.
Add your Icon to that folder.
I made this Icon. to represent a gameobject that will spawn in a player at the gameobjects location.
Add the following code to your script in the gameobject.
void OnDrawGizmos()
{
// Draws the player icon at position of the object.
// Because we draw it inside OnDrawGizmos the icon is also pickable
// in the scene view.
Gizmos.DrawIcon(transform.position, "player-icon.png", true);
}