diff --git a/pkgs/by-name/or/orion/package.nix b/pkgs/by-name/or/orion/package.nix
deleted file mode 100644
index f449aef5c875..000000000000
--- a/pkgs/by-name/or/orion/package.nix
+++ /dev/null
@@ -1,31 +0,0 @@
-{
-  lib,
-  stdenv,
-  fetchFromGitHub,
-  gtk-engine-murrine,
-}:
-
-stdenv.mkDerivation (finalAttrs: {
-  pname = "orion";
-  version = "1.5";
-
-  src = fetchFromGitHub {
-    owner = "shimmerproject";
-    repo = "Orion";
-    tag = "v${finalAttrs.version}";
-    sha256 = "1116yawv3fspkiq1ykk2wj0gza3l04b5nhldy0bayzjaj0y6fd89";
-  };
-
-  propagatedUserEnvPkgs = [ gtk-engine-murrine ];
-
-  installPhase = ''
-    mkdir -p $out/share/themes/orion
-    cp -r gtk-2.0 gtk-3.0 metacity-1 openbox-3 xfwm4 $out/share/themes/orion
-  '';
-
-  meta = {
-    homepage = "https://github.com/shimmerproject/Orion";
-    license = lib.licenses.gpl3Plus;
-    platforms = lib.platforms.linux;
-  };
-})
diff --git a/pkgs/development/python-modules/simple-parsing/default.nix b/pkgs/development/python-modules/simple-parsing/default.nix
index ed6f60301656..115473b31b5c 100644
--- a/pkgs/development/python-modules/simple-parsing/default.nix
+++ b/pkgs/development/python-modules/simple-parsing/default.nix
@@ -20,7 +20,6 @@
   # tests
   matplotlib,
   numpy,
-  orion,
   pytest-benchmark,
   pytest-regressions,
   pytestCheckHook,
@@ -61,7 +60,6 @@ buildPythonPackage (finalAttrs: {
   nativeCheckInputs = [
     matplotlib
     numpy
-    orion
     pytest-benchmark
     pytest-regressions
     pytestCheckHook
diff --git a/pkgs/top-level/aliases.nix b/pkgs/top-level/aliases.nix
index 6b61c67fd663..a17e4f92eea7 100644
--- a/pkgs/top-level/aliases.nix
+++ b/pkgs/top-level/aliases.nix
@@ -1767,6 +1767,7 @@ mapAliases {
   openzwave = throw "openzwave was removed because upstream is no longer maintained. Consider using zwave-js-server"; # Added 2026-05-14
   opera = throw "'opera' has been removed due to lack of maintenance in nixpkgs"; # Added 2025-05-19
   opusTools = warnAlias "'opusTools' has been renamed to 'opus-tools'" opus-tools; # Added 2026-02-12
+  orion = throw "'orion' was removed because it depended on the deprecated GTK2 engine."; # Added 2026-07-22
   orogene = throw "'orogene' uses a wasm-specific fork of async-tar that is vulnerable to CVE-2025-62518, which is not supported by its upstream"; # Added 2025-10-24
   ortp = throw "'ortp' has been moved to 'linphonePackages.ortp'"; # Added 2025-09-20
   OSCAR = throw "'OSCAR' has been renamed to/replaced by 'oscar'"; # Converted to throw 2025-10-27