ANTM/Assets/Editor/CharacterManagerEditor1.cs

using UnityEngine;
using UnityEditor;
using System.Collections;
using System.Collections.Generic;
using System.IO;

[CanEditMultipleObjects]
[CustomEditor(typeof(CharacterManager))]
public class CharacterManagerEditor : Editor
{

    public override void OnInspectorGUI()
    {
        CharacterManager myMenusController = target as CharacterManager;

        base.OnInspectorGUI();
        EditorGUILayout.Space();
        EditorGUILayout.LabelField("Tools:", EditorStyles.boldLabel);
        if (GUILayout.Button("Update All Characters)"))
        {
            Undo.RecordObject(myMenusController, "Update All Menus");
            myMenusController.NPCs = GettAllMenus();
        }
    }

    string[] GettAllMenus()
    {
        string[] allNames = Directory.GetFiles("Assets/Resources/NPCs", "*.prefab");

        for (int i = 0; i < allNames.Length; i++)
        {
            allNames[i] = Path.GetFileName(allNames[i]);
            allNames[i] = allNames[i].Remove(allNames[i].Length - 7);
        }

        return allNames;
    }

}