Sources

Wikipedia / official

hollowknight.wiki — comprehensive system docs (charms, bosses, lore).
Game UI Database — Hollow Knight — UI screenshot reference, source of all images here.

IGN, Polygon, Eurogamer reviews of Hollow Knight (2017) — broadly captured the metroidvania-meets-soulslike framing.
Noclip documentary on Team Cherry — multi-part dev-team interview covering the small-studio process and post-launch DLC strategy.
Game Maker's Toolkit — Mark Brown's video essay on Hollow Knight's level design (one of the most-cited GMT episodes).
Hollow Knight won several Best Indie / Best Metroidvania awards in 2017–18; it's the contemporary canonical 2D metroidvania alongside Ori and Axiom Verge.

Ari Gibson (Team Cherry, art / direction) — periodic interviews on the hand-drawn animation pipeline.
William Pellen (Team Cherry, programming / design) — interviews on the small-studio engineering approach.
David "Dave" Kazi — composer; the Hollow Knight OST is widely cited.
Christopher Larkin (additional music) — collaborator on the soundtrack.

All screenshots are from Game UI Database — Hollow Knight (id=113). The gallery has ~30 1920×1080 UI shots spanning HUD, menus, map screens, dialogue, and shop UI.

Boss arena screenshots — most of the iconic combat moments aren't UI shots; they'd come from Steam community, press kits, or capture from own play.
Dream Nail UI — the dream-realm encounters are visually distinctive but missing from the gameuidatabase set.
Pantheon UI — the boss-rush meta-content from the Godmaster DLC.

Hollow Knight 1.0 shipped February 2017; the four free DLCs (Hidden Dreams, Lifeblood, Grimm Troupe, Godmaster) added through 2018 are considered part of the canonical experience.
Some descriptions here (charm counts, notch budget) reflect the post-DLC final state; vanilla 1.0 had slightly fewer charms.
Silksong is in development as of writing; this entry covers Hollow Knight 1 only.