diff --git a/descriptions/AntiCheat.TheiaAntiTamper.md b/descriptions/AntiCheat.TheiaAntiTamper.md
new file mode 100644
index 000000000..c7c946b19
--- /dev/null
+++ b/descriptions/AntiCheat.TheiaAntiTamper.md
@@ -0,0 +1,2 @@
+Theia is an anti-tamper system developed by [**ZeroITLab**](https://zeroitlab.com/).
+Theia provides detections for tools commonly used to reverse engineer games such as IDA Pro, X64DBG and pe-bear.
diff --git a/rules.ini b/rules.ini
index 7488953e1..119a6e000 100644
--- a/rules.ini
+++ b/rules.ini
@@ -254,6 +254,7 @@ PunkBuster[] = (?:^|/)pbsv\.dll$
 PunkBuster[] = (?:^|/)Punkbuster(?:$|/)
 Ricochet = (?:^|/)Randgrid\.sys$
 TenProtect = (?:^|/)TP3Helper\.exe$
+TheiaAntiTamper = (?:^|/)preloader(?:_l)?\.dll$
 XIGNCODE3 = \.xem$
 
 [SDK]
diff --git a/tests/types/AntiCheat.TheiaAntiTamper.txt b/tests/types/AntiCheat.TheiaAntiTamper.txt
new file mode 100644
index 000000000..05aecdc59
--- /dev/null
+++ b/tests/types/AntiCheat.TheiaAntiTamper.txt
@@ -0,0 +1,8 @@
+/preloader.dll
+/preloader_l.dll
+preloader.dll
+preloader_l.dll
+Win64/preloader.dll
+Win64/preloader_l.dll
+Sub/Win64/preloader.dll
+Sub/Win64/preloader_l.dll