GameObject.FindGameObjectsWithTag

using UnityEngine;
using System.Collections;

public class ExampleClass : MonoBehaviour
{
public GameObject respawnPrefab;
public GameObject[] respawns;
void Start()
{
if (respawns == null)
respawns = GameObject.FindGameObjectsWithTag("Respawn");

foreach (GameObject respawn in respawns)
{
Instantiate(respawnPrefab, respawn.transform.position, respawn.transform.rotation);
}
}
}