The 9th century was defined by the calendar of Earth as occurring from the year 801 through the year 900.
- Kahless the Unforgettable unites the Klingon people after his defeat of the tyrant Molor and the Fek'Ihri. Kahless establishes a strict warrior code that is passed down through Klingon culture to the present day. (TNG: "Rightful Heir"; DS9: "The Sword of Kahless")
- A ferocious war breaks out on Solais V. The conflict lasts until the 24th century, at which point both sides are nearly wiped out. (TNG: "Loud As A Whisper")
- * According to Timicin, in either this century or the 4th century, there is no Resolution on Kaelon II. (TNG: "Half a Life")
|8th century||Timeline||10th century|