diff --git a/core/config/engine.h b/core/config/engine.h
index a0b1ffa98123..cf489a1785ad 100644
--- a/core/config/engine.h
+++ b/core/config/engine.h
@@ -34,7 +34,6 @@
 #include "core/os/main_loop.h"
 #include "core/string/ustring.h"
 #include "core/templates/list.h"
-#include "core/templates/vector.h"
 
 template <typename T>
 class TypedArray;
diff --git a/core/config/project_settings.cpp b/core/config/project_settings.cpp
index 562bde978e34..eedf23ece268 100644
--- a/core/config/project_settings.cpp
+++ b/core/config/project_settings.cpp
@@ -39,7 +39,6 @@
 #include "core/io/marshalls.h"
 #include "core/io/resource_uid.h"
 #include "core/object/script_language.h"
-#include "core/os/keyboard.h"
 #include "core/templates/rb_set.h"
 #include "core/variant/typed_array.h"
 #include "core/variant/variant_parser.h"
diff --git a/core/io/ip_address.h b/core/io/ip_address.h
index da7b0f77db1b..44c70643411e 100644
--- a/core/io/ip_address.h
+++ b/core/io/ip_address.h
@@ -41,8 +41,8 @@ struct IPAddress {
 		uint32_t field32[4];
 	};
 
-	bool valid;
-	bool wildcard;
+	bool valid = false;
+	bool wildcard = false;
 
 protected:
 	void _parse_ipv6(const String &p_string);
diff --git a/core/io/marshalls.h b/core/io/marshalls.h
index 6f015ac386e3..1e29f7c25544 100644
--- a/core/io/marshalls.h
+++ b/core/io/marshalls.h
@@ -85,7 +85,7 @@ static inline unsigned int encode_uint32(uint32_t p_uint, uint8_t *p_arr) {
 }
 
 static inline unsigned int encode_float(float p_float, uint8_t *p_arr) {
-	MarshallFloat mf;
+	MarshallFloat mf{};
 	mf.f = p_float;
 	encode_uint32(mf.i, p_arr);
 
@@ -103,7 +103,7 @@ static inline unsigned int encode_uint64(uint64_t p_uint, uint8_t *p_arr) {
 }
 
 static inline unsigned int encode_double(double p_double, uint8_t *p_arr) {
-	MarshallDouble md;
+	MarshallDouble md{};
 	md.d = p_double;
 	encode_uint64(md.l, p_arr);
 
@@ -121,7 +121,7 @@ static inline unsigned int encode_uintr(uintr_t p_uint, uint8_t *p_arr) {
 }
 
 static inline unsigned int encode_real(real_t p_real, uint8_t *p_arr) {
-	MarshallReal mr;
+	MarshallReal mr{};
 	mr.r = p_real;
 	encode_uintr(mr.i, p_arr);
 
@@ -173,7 +173,7 @@ static inline uint32_t decode_uint32(const uint8_t *p_arr) {
 }
 
 static inline float decode_float(const uint8_t *p_arr) {
-	MarshallFloat mf;
+	MarshallFloat mf{};
 	mf.i = decode_uint32(p_arr);
 	return mf.f;
 }
@@ -192,7 +192,7 @@ static inline uint64_t decode_uint64(const uint8_t *p_arr) {
 }
 
 static inline double decode_double(const uint8_t *p_arr) {
-	MarshallDouble md;
+	MarshallDouble md{};
 	md.l = decode_uint64(p_arr);
 	return md.d;
 }
diff --git a/core/math/color.h b/core/math/color.h
index 70fad78acbdd..0a3620da38eb 100644
--- a/core/math/color.h
+++ b/core/math/color.h
@@ -148,7 +148,7 @@ struct [[nodiscard]] Color {
 		union {
 			float f;
 			int32_t i;
-		} R, G, B, E;
+		} R{ 0.0f }, G{ 0.0f }, B{ 0.0f }, E{ 0.0f };
 
 		E.f = MaxChannel;
 		E.i += 0x07804000; // Add 15 to the exponent and 0x4000 to the mantissa
diff --git a/core/object/callable_method_pointer.h b/core/object/callable_method_pointer.h
index 86c66593bd3a..a41ac96d410c 100644
--- a/core/object/callable_method_pointer.h
+++ b/core/object/callable_method_pointer.h
@@ -41,8 +41,8 @@
 
 class CallableCustomMethodPointerBase : public CallableCustom {
 	uint32_t *comp_ptr = nullptr;
-	uint32_t comp_size;
-	uint32_t h;
+	uint32_t comp_size = 0U;
+	uint32_t h = 0U;
 #ifdef DEBUG_METHODS_ENABLED
 	const char *text = "";
 #endif
diff --git a/core/object/message_queue.h b/core/object/message_queue.h
index 673eb3845b55..64e244bda8b3 100644
--- a/core/object/message_queue.h
+++ b/core/object/message_queue.h
@@ -153,7 +153,7 @@ class CallQueue {
 	bool is_flushing() const;
 	int get_max_buffer_usage() const;
 
-	CallQueue(Allocator *p_custom_allocator = 0, uint32_t p_max_pages = 8192, const String &p_error_text = String());
+	CallQueue(Allocator *p_custom_allocator = nullptr, uint32_t p_max_pages = 8192, const String &p_error_text = String());
 	virtual ~CallQueue();
 };
 
diff --git a/core/templates/hashfuncs.h b/core/templates/hashfuncs.h
index 21eef10297ab..292151d1b6c8 100644
--- a/core/templates/hashfuncs.h
+++ b/core/templates/hashfuncs.h
@@ -130,7 +130,7 @@ static _FORCE_INLINE_ uint32_t hash_murmur3_one_float(float p_in, uint32_t p_see
 	union {
 		float f;
 		uint32_t i;
-	} u;
+	} u = { 0.0f };
 
 	// Normalize +/- 0.0 and NaN values so they hash the same.
 	if (p_in == 0.0f) {
@@ -153,7 +153,7 @@ static _FORCE_INLINE_ uint32_t hash_murmur3_one_double(double p_in, uint32_t p_s
 	union {
 		double d;
 		uint64_t i;
-	} u;
+	} u = { 0.0 };
 
 	// Normalize +/- 0.0 and NaN values so they hash the same.
 	if (p_in == 0.0f) {
@@ -241,7 +241,7 @@ static _FORCE_INLINE_ uint32_t hash_djb2_one_float(double p_in, uint32_t p_prev
 	union {
 		double d;
 		uint64_t i;
-	} u;
+	} u = { 0.0 };
 
 	// Normalize +/- 0.0 and NaN values so they hash the same.
 	if (p_in == 0.0f) {
@@ -270,7 +270,7 @@ static _FORCE_INLINE_ uint64_t hash_djb2_one_float_64(double p_in, uint64_t p_pr
 	union {
 		double d;
 		uint64_t i;
-	} u;
+	} u = { 0.0 };
 
 	// Normalize +/- 0.0 and NaN values so they hash the same.
 	if (p_in == 0.0f) {
diff --git a/core/templates/safe_refcount.h b/core/templates/safe_refcount.h
index 16b605eaffbb..120f376e7374 100644
--- a/core/templates/safe_refcount.h
+++ b/core/templates/safe_refcount.h
@@ -152,7 +152,7 @@ class SafeNumeric {
 };
 
 class SafeFlag {
-	std::atomic_bool flag;
+	std::atomic_bool flag = false;
 
 	static_assert(std::atomic_bool::is_always_lock_free);
 
diff --git a/core/variant/variant.h b/core/variant/variant.h
index c76b849abdb7..3f7f721409a5 100644
--- a/core/variant/variant.h
+++ b/core/variant/variant.h
@@ -814,8 +814,7 @@ class Variant {
 	static void unregister_types();
 
 	Variant(const Variant &p_variant);
-	_FORCE_INLINE_ Variant() :
-			type(NIL) {}
+	_FORCE_INLINE_ Variant() {}
 	_FORCE_INLINE_ ~Variant() {
 		clear();
 	}