The guests
Cameos
Former houseguests and other franchise figures who appeared during Big Brother 21.
| Guest | When | Appearance |
|---|---|---|
| Kaycee | Week 1, aired Tue Jul 2, 2019 | Hosted the Power of Veto competition. |
| Winston | Week 2, aired Sun Jul 7, 2019 | Appeared in a Love Island video message shown to the houseguests. |
| Brett | Week 2, aired Sun Jul 7, 2019 | Appeared in a Love Island video message shown to the houseguests. |
| Bayleigh | Week 2, aired Sun Jul 7, 2019 | Appeared in a Love Island video message shown to the houseguests. |
| Swaggy C | Week 2, aired Sun Jul 7, 2019 | Appeared in a Love Island video message shown to the houseguests. |
| Tyler | Week 2, aired Wed Jul 10, 2019 | Hosted the Power of Veto competition. |
| Kaitlyn | Week 3, aired Wed Jul 17, 2019 | Hosted the Power of Veto competition. |
| Zingbot | Week 9, aired Wed Aug 28, 2019 | Returned to the house to roast the houseguests. |
| Swaggy C | Week 11, aired Sun Sep 8, 2019 | Hosted the Head of Household competition with Bayleigh. |
| Bayleigh | Week 11, aired Sun Sep 8, 2019 | Hosted the Head of Household competition with Swaggy C. |
| Kaycee | Week 13, aired Sun Sep 22, 2019 | Joined Julie Chen Moonves to discuss the season. |
| Tyler | Week 13, aired Sun Sep 22, 2019 | Joined Julie Chen Moonves to discuss the season. |
| JC | Week 13, aired Sun Sep 22, 2019 | Joined Julie Chen Moonves to discuss the season. |