diff --git a/BUILD b/BUILD
index ec8bed94f53..421d47fc4eb 100644
--- a/BUILD
+++ b/BUILD
@@ -227,11 +227,11 @@ config_setting(
 python_config_settings()
 
 # This should be updated along with build_handwritten.yaml
-g_stands_for = "gnarly"  # @unused
+g_stands_for = "gladiator"  # @unused
 
 core_version = "42.0.0"  # @unused
 
-version = "1.65.0-dev"  # @unused
+version = "1.66.0-dev"  # @unused
 
 GPR_PUBLIC_HDRS = [
     "include/grpc/support/alloc.h",
diff --git a/build_handwritten.yaml b/build_handwritten.yaml
index 33d07a997bf..a962dae84f8 100644
--- a/build_handwritten.yaml
+++ b/build_handwritten.yaml
@@ -14,9 +14,9 @@ settings:
   '#10': See the expand_version.py for all the quirks here
   core_version: 42.0.0
   csharp_major_version: 2
-  g_stands_for: gnarly
+  g_stands_for: gladiator
   protobuf_version: 3.26.1
-  version: 1.65.0-dev
+  version: 1.66.0-dev
 configs:
   asan:
     CC: clang
diff --git a/doc/g_stands_for.md b/doc/g_stands_for.md
index 2557a2f352e..035601582a7 100644
--- a/doc/g_stands_for.md
+++ b/doc/g_stands_for.md
@@ -64,4 +64,5 @@
 - 1.62 'g' stands for ['guardian'](https://github.com/grpc/grpc/tree/v1.62.x)
 - 1.63 'g' stands for ['giggle'](https://github.com/grpc/grpc/tree/v1.63.x)
 - 1.64 'g' stands for ['grateful'](https://github.com/grpc/grpc/tree/v1.64.x)
-- 1.65 'g' stands for ['gnarly'](https://github.com/grpc/grpc/tree/master)
+- 1.65 'g' stands for ['gnarly'](https://github.com/grpc/grpc/tree/v1.65.x)
+- 1.66 'g' stands for ['gladiator'](https://github.com/grpc/grpc/tree/master)