| Millennium: | 1st millennium |
|---|---|
| Centuries: | 1st century BC – 1st century – 2nd century |
| Decades: | 0s BC 0s 10s – 20s – 30s 40s 50s |
| Years: | 20 21 22 – 23 – 24 25 26 |
| Gregorian calendar | AD 23 XXIII |
| Ab urbe condita | 776 |
| Assyrian calendar | 4773 |
| Balinese saka calendar | N/A |
| Bengali calendar | −570 |
| Berber calendar | 973 |
| Buddhist calendar | 567 |
| Burmese calendar | −615 |
| Byzantine calendar | 5531–5532 |
| Chinese calendar | 壬午年 (Water Horse) 2719 or 2659 — to — 癸未年 (Water Goat) 2720 or 2660 |
| Coptic calendar | −261 – −260 |
| Discordian calendar | 1189 |
| Ethiopian calendar | 15–16 |
| Hebrew calendar | 3783–3784 |
| Hindu calendars | |
| - Vikram Samvat | 79–80 |
| - Shaka Samvat | N/A |
| - Kali Yuga | 3123–3124 |
| Holocene calendar | 10023 |
| Iranian calendar | 599 BP – 598 BP |
| Islamic calendar | 617 BH – 616 BH |
| Javanese calendar | N/A |
| Julian calendar | AD 23 XXIII |
| Korean calendar | 2356 |
| Minguo calendar | 1889 before ROC 民前1889年 |
| Nanakshahi calendar | −1445 |
| Seleucid era | 334/335 AG |
| Thai solar calendar | 565–566 |
| Tibetan calendar | 阳水马年 (male Water-Horse) 149 or −232 or −1004 — to — 阴水羊年 (female Water-Goat) 150 or −231 or −1003 |
23 (XXIII) was a common year starting on Friday of the Julian calendar, the 23rd year of the Common Era (CE) and Anno Domini (AD) designations, the 23rd year of the 1st millennium, the 23rd year of the 1st century, and the 4th year of the 20s decade. As of the start of 23, the Gregorian calendar was 2 days behind the Julian calendar, which was the dominant calendar of the time.