diff --git a/src/components/nostr/GrimoireUsername.tsx b/src/components/nostr/GrimoireUsername.tsx
new file mode 100644
index 0000000..5a9fa37
--- /dev/null
+++ b/src/components/nostr/GrimoireUsername.tsx
@@ -0,0 +1,72 @@
+import { getGrimoireMember } from "@/lib/grimoire-members";
+import { BookOpen } from "lucide-react";
+import { cn } from "@/lib/utils";
+
+/**
+ * Grimoire Username Component
+ *
+ * Displays Grimoire member usernames with special styling and verification badge.
+ * If the pubkey belongs to a Grimoire member, shows their custom username
+ * with a Grimoire badge icon. Otherwise returns null.
+ */
+export function GrimoireUsername({
+  pubkey,
+  className,
+  showIcon = true,
+}: {
+  pubkey: string;
+  className?: string;
+  showIcon?: boolean;
+}) {
+  const member = getGrimoireMember(pubkey);
+
+  if (!member) {
+    return null;
+  }
+
+  return (
+    <span
+      className={cn(
+        "inline-flex items-center gap-1.5 text-accent font-medium",
+        className,
+      )}
+      title={`Grimoire member: ${member.nip05}`}
+    >
+      <span>{member.username}@grimoire.pro</span>
+      {showIcon && (
+        <BookOpen
+          className="h-3.5 w-3.5 text-accent"
+          aria-label="Grimoire member"
+        />
+      )}
+    </span>
+  );
+}
+
+/**
+ * Grimoire Badge Component
+ *
+ * Shows just the verification badge icon for Grimoire members.
+ * Useful for adding next to existing username displays.
+ */
+export function GrimoireBadge({
+  pubkey,
+  className,
+}: {
+  pubkey: string;
+  className?: string;
+}) {
+  const member = getGrimoireMember(pubkey);
+
+  if (!member) {
+    return null;
+  }
+
+  return (
+    <BookOpen
+      className={cn("h-3.5 w-3.5 text-accent", className)}
+      title={`Grimoire member: ${member.nip05}`}
+      aria-label="Grimoire member"
+    />
+  );
+}
diff --git a/src/components/nostr/UserName.tsx b/src/components/nostr/UserName.tsx
index 551e86c..96e1ac2 100644
--- a/src/components/nostr/UserName.tsx
+++ b/src/components/nostr/UserName.tsx
@@ -2,6 +2,7 @@ import { useProfile } from "@/hooks/useProfile";
 import { getDisplayName } from "@/lib/nostr-utils";
 import { cn } from "@/lib/utils";
 import { useGrimoire } from "@/core/state";
+import { GrimoireBadge } from "./GrimoireUsername";
 
 interface UserNameProps {
   pubkey: string;
@@ -14,6 +15,7 @@ interface UserNameProps {
  * Shows placeholder derived from pubkey while loading or if no profile exists
  * Clicking opens the user's profile
  * Uses highlight color for the logged-in user (themeable amber)
+ * Shows Grimoire badge for Grimoire members
  */
 export function UserName({ pubkey, isMention, className }: UserNameProps) {
   const { addWindow, state } = useGrimoire();
@@ -32,14 +34,17 @@ export function UserName({ pubkey, isMention, className }: UserNameProps) {
     <span
       dir="auto"
       className={cn(
-        "font-semibold cursor-crosshair hover:underline hover:decoration-dotted",
+        "inline-flex items-center gap-1.5 font-semibold cursor-crosshair hover:underline hover:decoration-dotted",
         isActiveAccount ? "text-highlight" : "text-accent",
         className,
       )}
       onClick={handleClick}
     >
-      {isMention ? "@" : null}
-      {displayName}
+      <span>
+        {isMention ? "@" : null}
+        {displayName}
+      </span>
+      <GrimoireBadge pubkey={pubkey} />
     </span>
   );
 }
diff --git a/src/components/nostr/nip05.tsx b/src/components/nostr/nip05.tsx
index d4c247d..a201216 100644
--- a/src/components/nostr/nip05.tsx
+++ b/src/components/nostr/nip05.tsx
@@ -1,5 +1,7 @@
 import { useNip05 } from "@/hooks/useNip05";
 import { ProfileContent } from "applesauce-core/helpers";
+import { GrimoireUsername } from "./GrimoireUsername";
+import { isGrimoireMember } from "@/lib/grimoire-members";
 
 export function QueryNip05({
   pubkey,
@@ -20,6 +22,12 @@ export default function Nip05({
   pubkey: string;
   profile: ProfileContent;
 }) {
+  // Check if this is a Grimoire member first - they get special display
+  if (isGrimoireMember(pubkey)) {
+    return <GrimoireUsername pubkey={pubkey} />;
+  }
+
+  // Otherwise show regular NIP-05 if available
   if (!profile?.nip05) return null;
   return <QueryNip05 pubkey={pubkey} nip05={profile.nip05} />;
 }
diff --git a/src/lib/grimoire-members.test.ts b/src/lib/grimoire-members.test.ts
new file mode 100644
index 0000000..297a241
--- /dev/null
+++ b/src/lib/grimoire-members.test.ts
@@ -0,0 +1,135 @@
+import { describe, it, expect } from "vitest";
+import {
+  GRIMOIRE_MEMBERS,
+  isGrimoireMember,
+  getGrimoireMember,
+  getGrimoireMemberByNip05,
+  getGrimoireUsername,
+  getGrimoireNip05,
+} from "./grimoire-members";
+
+describe("Grimoire Members", () => {
+  const underscorePubkey =
+    "ce3cd5ba3ae52cec4e4b267fb29f1d2a526a5f4b8e8475d8a603a63c8925295f";
+  const verbirichaPubkey =
+    "7fa56f5d6962ab1e3cd424e758c3002b8665f7b0d8dcee9fe9e288d7751ac194";
+  const randomPubkey =
+    "0000000000000000000000000000000000000000000000000000000000000000";
+
+  describe("GRIMOIRE_MEMBERS", () => {
+    it("should contain exactly 2 members", () => {
+      expect(GRIMOIRE_MEMBERS).toHaveLength(2);
+    });
+
+    it("should have correct structure for all members", () => {
+      for (const member of GRIMOIRE_MEMBERS) {
+        expect(member).toHaveProperty("username");
+        expect(member).toHaveProperty("pubkey");
+        expect(member).toHaveProperty("nip05");
+        expect(typeof member.username).toBe("string");
+        expect(typeof member.pubkey).toBe("string");
+        expect(typeof member.nip05).toBe("string");
+        expect(member.pubkey).toHaveLength(64); // Hex pubkey
+      }
+    });
+  });
+
+  describe("isGrimoireMember", () => {
+    it("should return true for _ member", () => {
+      expect(isGrimoireMember(underscorePubkey)).toBe(true);
+    });
+
+    it("should return true for verbiricha member", () => {
+      expect(isGrimoireMember(verbirichaPubkey)).toBe(true);
+    });
+
+    it("should return false for non-member", () => {
+      expect(isGrimoireMember(randomPubkey)).toBe(false);
+    });
+
+    it("should be case-insensitive", () => {
+      expect(isGrimoireMember(underscorePubkey.toUpperCase())).toBe(true);
+      expect(isGrimoireMember(verbirichaPubkey.toUpperCase())).toBe(true);
+    });
+  });
+
+  describe("getGrimoireMember", () => {
+    it("should return member info for _ username", () => {
+      const member = getGrimoireMember(underscorePubkey);
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("_");
+      expect(member?.pubkey).toBe(underscorePubkey);
+      expect(member?.nip05).toBe("_@grimoire.pro");
+    });
+
+    it("should return member info for verbiricha username", () => {
+      const member = getGrimoireMember(verbirichaPubkey);
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("verbiricha");
+      expect(member?.pubkey).toBe(verbirichaPubkey);
+      expect(member?.nip05).toBe("verbiricha@grimoire.pro");
+    });
+
+    it("should return undefined for non-member", () => {
+      const member = getGrimoireMember(randomPubkey);
+      expect(member).toBeUndefined();
+    });
+
+    it("should be case-insensitive", () => {
+      const member = getGrimoireMember(underscorePubkey.toUpperCase());
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("_");
+    });
+  });
+
+  describe("getGrimoireMemberByNip05", () => {
+    it("should return member info for _@grimoire.pro", () => {
+      const member = getGrimoireMemberByNip05("_@grimoire.pro");
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("_");
+      expect(member?.pubkey).toBe(underscorePubkey);
+    });
+
+    it("should return member info for verbiricha@grimoire.pro", () => {
+      const member = getGrimoireMemberByNip05("verbiricha@grimoire.pro");
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("verbiricha");
+      expect(member?.pubkey).toBe(verbirichaPubkey);
+    });
+
+    it("should return undefined for non-member identifier", () => {
+      const member = getGrimoireMemberByNip05("alice@example.com");
+      expect(member).toBeUndefined();
+    });
+
+    it("should be case-insensitive", () => {
+      const member = getGrimoireMemberByNip05("_@GRIMOIRE.PRO");
+      expect(member).toBeDefined();
+      expect(member?.username).toBe("_");
+    });
+  });
+
+  describe("getGrimoireUsername", () => {
+    it("should return username for member", () => {
+      expect(getGrimoireUsername(underscorePubkey)).toBe("_");
+      expect(getGrimoireUsername(verbirichaPubkey)).toBe("verbiricha");
+    });
+
+    it("should return undefined for non-member", () => {
+      expect(getGrimoireUsername(randomPubkey)).toBeUndefined();
+    });
+  });
+
+  describe("getGrimoireNip05", () => {
+    it("should return NIP-05 for member", () => {
+      expect(getGrimoireNip05(underscorePubkey)).toBe("_@grimoire.pro");
+      expect(getGrimoireNip05(verbirichaPubkey)).toBe(
+        "verbiricha@grimoire.pro",
+      );
+    });
+
+    it("should return undefined for non-member", () => {
+      expect(getGrimoireNip05(randomPubkey)).toBeUndefined();
+    });
+  });
+});
diff --git a/src/lib/grimoire-members.ts b/src/lib/grimoire-members.ts
new file mode 100644
index 0000000..b238599
--- /dev/null
+++ b/src/lib/grimoire-members.ts
@@ -0,0 +1,96 @@
+/**
+ * Grimoire Member System
+ *
+ * Defines special usernames for Grimoire project members with custom NIP-05 style identifiers.
+ * Members get special visual styling and verification badges.
+ */
+
+/**
+ * Grimoire member definition
+ */
+export interface GrimoireMember {
+  /** Username for display (e.g., "_", "verbiricha") */
+  username: string;
+  /** Hex pubkey */
+  pubkey: string;
+  /** NIP-05 style identifier (e.g., "_@grimoire.pro") */
+  nip05: string;
+}
+
+/**
+ * Official Grimoire project members
+ * These users get special username styling and verification badges
+ */
+export const GRIMOIRE_MEMBERS: readonly GrimoireMember[] = [
+  {
+    username: "_",
+    pubkey: "ce3cd5ba3ae52cec4e4b267fb29f1d2a526a5f4b8e8475d8a603a63c8925295f",
+    nip05: "_@grimoire.pro",
+  },
+  {
+    username: "verbiricha",
+    pubkey: "7fa56f5d6962ab1e3cd424e758c3002b8665f7b0d8dcee9fe9e288d7751ac194",
+    nip05: "verbiricha@grimoire.pro",
+  },
+] as const;
+
+/**
+ * Map of pubkey -> member for O(1) lookups
+ */
+const membersByPubkey = new Map<string, GrimoireMember>(
+  GRIMOIRE_MEMBERS.map((member) => [member.pubkey, member]),
+);
+
+/**
+ * Map of NIP-05 identifier -> member for O(1) lookups
+ */
+const membersByNip05 = new Map<string, GrimoireMember>(
+  GRIMOIRE_MEMBERS.map((member) => [member.nip05, member]),
+);
+
+/**
+ * Check if a pubkey belongs to a Grimoire member
+ * @param pubkey - Hex public key
+ * @returns true if user is a Grimoire member
+ */
+export function isGrimoireMember(pubkey: string): boolean {
+  return membersByPubkey.has(pubkey.toLowerCase());
+}
+
+/**
+ * Get Grimoire member info by pubkey
+ * @param pubkey - Hex public key
+ * @returns Member info or undefined
+ */
+export function getGrimoireMember(pubkey: string): GrimoireMember | undefined {
+  return membersByPubkey.get(pubkey.toLowerCase());
+}
+
+/**
+ * Get Grimoire member info by NIP-05 identifier
+ * @param nip05 - NIP-05 identifier (e.g., "_@grimoire.pro")
+ * @returns Member info or undefined
+ */
+export function getGrimoireMemberByNip05(
+  nip05: string,
+): GrimoireMember | undefined {
+  return membersByNip05.get(nip05.toLowerCase());
+}
+
+/**
+ * Get Grimoire username for a pubkey
+ * @param pubkey - Hex public key
+ * @returns Username or undefined if not a member
+ */
+export function getGrimoireUsername(pubkey: string): string | undefined {
+  return membersByPubkey.get(pubkey.toLowerCase())?.username;
+}
+
+/**
+ * Get Grimoire NIP-05 identifier for a pubkey
+ * @param pubkey - Hex public key
+ * @returns NIP-05 identifier or undefined if not a member
+ */
+export function getGrimoireNip05(pubkey: string): string | undefined {
+  return membersByPubkey.get(pubkey.toLowerCase())?.nip05;
+}
diff --git a/src/lib/nip05.test.ts b/src/lib/nip05.test.ts
new file mode 100644
index 0000000..2e04a91
--- /dev/null
+++ b/src/lib/nip05.test.ts
@@ -0,0 +1,28 @@
+import { describe, it, expect } from "vitest";
+import { nip19 } from "nostr-tools";
+
+describe("NIP-19 Decoding for Grimoire Members", () => {
+  it("should decode npub for _ username", () => {
+    const npub =
+      "npub1eras6w483zu6ee8kewfdm97n72fdkfd4e8ujgch0d3jfycfflwhsytskz0";
+    const decoded = nip19.decode(npub);
+
+    expect(decoded.type).toBe("npub");
+    expect(decoded.data).toBe(
+      "ce3cd5ba3ae52cec4e4b267fb29f1d2a526a5f4b8e8475d8a603a63c8925295f",
+    );
+  });
+
+  it("should decode nprofile for verbiricha username", () => {
+    const nprofile =
+      "nprofile1qy28wumn8ghj7mrfva58gmnfdenjuun9vshszxnhwden5te0wpuhyctdd9jzuenfv96x5ctx9e3k7mf0qydhwumn8ghj7argv4nx7un9wd6zumn0wd68yvfwvdhk6tcpz9mhxue69uhkummnw3ezuamfdejj7qpq07jk7htfv243u0x5ynn43scq9wrxtaasmrwwa8lfu2ydwag6cx2qsan62z";
+    const decoded = nip19.decode(nprofile);
+
+    expect(decoded.type).toBe("nprofile");
+    if (decoded.type === "nprofile") {
+      expect(decoded.data.pubkey).toBe(
+        "7fa56f5d6962ab1e3cd424e758c3002b8665f7b0d8dcee9fe9e288d7751ac194",
+      );
+    }
+  });
+});