Firsts
| First discovered | Name | Date | Notes |
|---|---|---|---|
| Galaxy cluster | Virgo Cluster | 1784 | Discovered by Charles Messier. |
| Galaxy group | |||
| Compact group | The four brightest members of Stephan's Quintet | 1877 | Discovered by Edouard Stephan. |
| Proto-cluster | |||
| Double galaxy | Magellanic Clouds | antiquity |
Read more about this topic: List Of Galaxy Clusters