Hornet

First Encounter, Greenpath
When travelling through the area, she will appear several times, but will quickly dash away. When approached at the end of the zone, she is standing by the body of another vessel. She says that she can sense something awakening within Hallownest and that she knows the nature of The Knight, and because of that, she cannot allow them to proceed.

Second Encounter, City of Tears
Hornet will appear briefly outside the Fungal Wastes entrance to the City of Tears. Once The Knight reaches the statue of The Hollow Knight, she will appear again and tell them to seek "the grave in ash" if they wish to seek a role in Hallownest's perpetuation. This will not occur if she was already encountered at Kingdom's Edge.

Third Encounter, Kingdom's Edge
Hornet is next encountered in the far east area of Kingdom's Edge, which requires the Monarch Wings to reach. Upon meeting Hornet here, she will challenge The Knight to one more battle to prove that they are worthy to see the truth about Hallownest.

Fourth Encounter, The Abyss
After obtaining the Shade Cloak upgrade, she will appear at the top of the area, telling The Knight that there are two choices ahead of them; to prolong the world's stasis, or face the source of the plague.

Fifth Encounter, Deepnest
If defeated in Kingdom's Edge and if the player has acquired the King's Brand before facing Herrah the Beast, she will appear after The Knight has undone Herrah's seal. Unlike other instances, she does not offer advice or clues, but is simply there to mourn the passing of her mother.

Final Encounter, Final Boss
If the player has acquired Void Heart, Hornet appears outside the Temple of the Black Egg, telling The Knight that she cannot follow them inside, but will help if the opportunity presents itself.

Trivia
"'Quick with her deadly needle, relentless in battle, Hornet is exploring Hallownest to find the answer to a riddle that has plagued her. She has so far resisted the infection, but will still cut you down if you stand in her path."
 * Hornet was revealed in one of the Kickstarter updates:

"You may catch glimpses of Hornet during your exploration of Hallownest, although she always seems to be one or two steps ahead of you. If you do manage to catch up with her, be wary! Her needle can cut a bug down from thirty yards.'"


 * One of the Kickstarter goals (for AU$ 56,000) was Hornet to receive her own DLC in a later update and becoming the second playable character. This goal was reached and her DLC will involve her fighting an Assassin Bug several times as a backer boss character.


 * Hornet is the child of Herrah the Beast, though whether or not she is biologically her daughter is unclear. Herrah traded her allegiance (she previously did not accept the Pale King's rule) and took on the role of a Dreamer in exchange for a child.


 * Hornet herself says that she shares the source of her power with The Knight, though she lacks the emptiness which makes them a suitable vessel.

Хорнет
 * Team Cherry announced that Hornet will be a playable character in an upcoming DLC patch.