diff --git a/Marlin/M100_Free_Mem_Chk.cpp b/Marlin/M100_Free_Mem_Chk.cpp
index f7900a0f3..6033c0afe 100644
--- a/Marlin/M100_Free_Mem_Chk.cpp
+++ b/Marlin/M100_Free_Mem_Chk.cpp
@@ -137,8 +137,10 @@ void gcode_M100() {
   // other vital statistics that define the memory pool.
   //
   if (code_seen('F')) {
-    int max_addr = (int) __brkval;
-    int max_cnt = 0;
+    #if 0
+      int max_addr = (int) __brkval;
+      int max_cnt = 0;
+    #endif
     int block_cnt = 0;
     ptr = (unsigned char*) __brkval;
     sp = top_of_stack();
@@ -155,10 +157,12 @@ void gcode_M100() {
           i += j;
           block_cnt++;
         }
-        if (j > max_cnt) {      // We don't do anything with this information yet
-          max_cnt  = j;     // but we do know where the biggest free memory block is.
-          max_addr = (int) ptr + i;
-        }
+        #if 0
+          if (j > max_cnt) {      // We don't do anything with this information yet
+            max_cnt  = j;     // but we do know where the biggest free memory block is.
+            max_addr = (int) ptr + i;
+          }
+        #endif
       }
     }
     if (block_cnt > 1)
diff --git a/Marlin/Marlin_main.cpp b/Marlin/Marlin_main.cpp
index 99192f4f1..cd91b8d91 100644
--- a/Marlin/Marlin_main.cpp
+++ b/Marlin/Marlin_main.cpp
@@ -1638,6 +1638,9 @@ static void setup_for_endstop_move() {
   }
 
   static void stow_z_probe(bool doRaise = true) {
+    #if !(HAS_SERVO_ENDSTOPS && (Z_RAISE_AFTER_PROBING > 0))
+      UNUSED(doRaise);
+    #endif
     #if ENABLED(DEBUG_LEVELING_FEATURE)
       if (DEBUGGING(LEVELING)) {
         print_xyz("stow_z_probe > current_position", current_position);
@@ -1912,11 +1915,13 @@ static void setup_for_endstop_move() {
 
 #endif // AUTO_BED_LEVELING_FEATURE
 
-static void axis_unhomed_error() {
-  LCD_MESSAGEPGM(MSG_YX_UNHOMED);
-  SERIAL_ECHO_START;
-  SERIAL_ECHOLNPGM(MSG_YX_UNHOMED);
-}
+#if ENABLED(Z_PROBE_SLED) || ENABLED(Z_SAFE_HOMING) || ENABLED(AUTO_BED_LEVELING_FEATURE)
+  static void axis_unhomed_error() {
+    LCD_MESSAGEPGM(MSG_YX_UNHOMED);
+    SERIAL_ECHO_START;
+    SERIAL_ECHOLNPGM(MSG_YX_UNHOMED);
+  }
+#endif
 
 #if ENABLED(Z_PROBE_SLED)
 
@@ -2300,6 +2305,8 @@ void unknown_command_error() {
           SERIAL_ECHO_START;
           SERIAL_ECHOLNPGM(MSG_BUSY_PAUSED_FOR_INPUT);
           break;
+        default:
+          break;
       }
     }
     next_busy_signal_ms = ms + 10000UL; // "busy: ..." message every 10s
@@ -3820,7 +3827,7 @@ inline void gcode_M42() {
     }
 
     double sum = 0.0, mean = 0.0, sigma = 0.0, sample_set[50];
-    uint8_t verbose_level = 1, n_samples = 10, n_legs = 0, schizoid_flag = 0;
+    int8_t verbose_level = 1, n_samples = 10, n_legs = 0, schizoid_flag = 0;
 
     if (code_seen('V')) {
       verbose_level = code_value_short();
@@ -5476,7 +5483,7 @@ inline void gcode_M400() { st_synchronize(); }
     if (delay_index2 == -1) { //initialize the ring buffer if it has not been done since startup
       int temp_ratio = widthFil_to_size_ratio();
 
-      for (delay_index1 = 0; delay_index1 < COUNT(measurement_delay); ++delay_index1)
+      for (delay_index1 = 0; delay_index1 < (int)COUNT(measurement_delay); ++delay_index1)
         measurement_delay[delay_index1] = temp_ratio - 100;  //subtract 100 to scale within a signed byte
 
       delay_index1 = delay_index2 = 0;
@@ -5525,7 +5532,7 @@ inline void gcode_M410() { quickStop(); }
    * M421: Set a single Mesh Bed Leveling Z coordinate
    */
   inline void gcode_M421() {
-    float x, y, z;
+    float x = 0, y = 0, z = 0;
     bool err = false, hasX, hasY, hasZ;
     if ((hasX = code_seen('X'))) x = code_value();
     if ((hasY = code_seen('Y'))) y = code_value();
@@ -5688,7 +5695,10 @@ inline void gcode_M503() {
       return;
     }
 
-    float lastpos[NUM_AXIS], fr60 = feedrate / 60;
+    float lastpos[NUM_AXIS];
+    #if ENABLED(DELTA)
+      float fr60 = feedrate / 60;
+    #endif
 
     for (int i = 0; i < NUM_AXIS; i++)
       lastpos[i] = destination[i] = current_position[i];
@@ -5745,7 +5755,9 @@ inline void gcode_M503() {
     disable_e3();
     delay(100);
     LCD_ALERTMESSAGEPGM(MSG_FILAMENTCHANGE);
-    millis_t next_tick = 0;
+    #if DISABLED(AUTO_FILAMENT_CHANGE)
+      millis_t next_tick = 0;
+    #endif
     KEEPALIVE_STATE(PAUSED_FOR_USER);
     while (!lcd_clicked()) {
       #if DISABLED(AUTO_FILAMENT_CHANGE)
diff --git a/Marlin/Sd2Card.cpp b/Marlin/Sd2Card.cpp
index 53935feb1..62416b068 100644
--- a/Marlin/Sd2Card.cpp
+++ b/Marlin/Sd2Card.cpp
@@ -365,6 +365,7 @@ bool Sd2Card::init(uint8_t sckRateID, uint8_t chipSelectPin) {
   #if DISABLED(SOFTWARE_SPI)
     return setSckRate(sckRateID);
   #else  // SOFTWARE_SPI
+    UNUSED(sckRateID);
     return true;
   #endif  // SOFTWARE_SPI
 
diff --git a/Marlin/cardreader.cpp b/Marlin/cardreader.cpp
index c122a45ce..eabf7b08b 100644
--- a/Marlin/cardreader.cpp
+++ b/Marlin/cardreader.cpp
@@ -348,11 +348,11 @@ void CardReader::openFile(char* name, bool read, bool push_current/*=false*/) {
   char *dirname_start, *dirname_end;
   if (name[0] == '/') {
     dirname_start = &name[1];
-    while (dirname_start > 0) {
+    while (dirname_start != NULL) {
       dirname_end = strchr(dirname_start, '/');
       //SERIAL_ECHO("start:");SERIAL_ECHOLN((int)(dirname_start - name));
       //SERIAL_ECHO("end  :");SERIAL_ECHOLN((int)(dirname_end - name));
-      if (dirname_end > 0 && dirname_end > dirname_start) {
+      if (dirname_end != NULL && dirname_end > dirname_start) {
         char subdirname[FILENAME_LENGTH];
         strncpy(subdirname, dirname_start, dirname_end - dirname_start);
         subdirname[dirname_end - dirname_start] = 0;
@@ -429,11 +429,11 @@ void CardReader::removeFile(char* name) {
   char *dirname_start, *dirname_end;
   if (name[0] == '/') {
     dirname_start = strchr(name, '/') + 1;
-    while (dirname_start > 0) {
+    while (dirname_start != NULL) {
       dirname_end = strchr(dirname_start, '/');
       //SERIAL_ECHO("start:");SERIAL_ECHOLN((int)(dirname_start - name));
       //SERIAL_ECHO("end  :");SERIAL_ECHOLN((int)(dirname_end - name));
-      if (dirname_end > 0 && dirname_end > dirname_start) {
+      if (dirname_end != NULL && dirname_end > dirname_start) {
         char subdirname[FILENAME_LENGTH];
         strncpy(subdirname, dirname_start, dirname_end - dirname_start);
         subdirname[dirname_end - dirname_start] = 0;
diff --git a/Marlin/temperature.h b/Marlin/temperature.h
index d6674b5a7..edccdfc5d 100644
--- a/Marlin/temperature.h
+++ b/Marlin/temperature.h
@@ -83,7 +83,7 @@ extern float current_temperature_bed;
 
   #if ENABLED(PID_PARAMS_PER_EXTRUDER)
     extern float Kp[EXTRUDERS], Ki[EXTRUDERS], Kd[EXTRUDERS], Kc[EXTRUDERS]; // one param per extruder
-    #define PID_PARAM(param,e) param[e] // use macro to point to array value
+    #define PID_PARAM(param, e) param[e] // use macro to point to array value
   #else
     extern float Kp, Ki, Kd, Kc; // one param per extruder - saves 20 or 36 bytes of ram (inc array pointer)
     #define PID_PARAM(param, e) param // use macro to point directly to value
diff --git a/Marlin/ultralcd.cpp b/Marlin/ultralcd.cpp
index 0474830db..483d021fe 100644
--- a/Marlin/ultralcd.cpp
+++ b/Marlin/ultralcd.cpp
@@ -755,6 +755,8 @@ void _lcd_preheat(int endnum, const float temph, const float tempb, const int fa
   if (temph > 0) setTargetHotend(temph, endnum);
   #if TEMP_SENSOR_BED != 0
     setTargetBed(tempb);
+  #else
+    UNUSED(tempb);
   #endif
   #if FAN_COUNT > 0
     #if FAN_COUNT > 1
@@ -762,6 +764,8 @@ void _lcd_preheat(int endnum, const float temph, const float tempb, const int fa
     #else
       fanSpeeds[0] = fan;
     #endif
+  #else
+    UNUSED(fan);
   #endif
   lcd_return_to_status();
 }
@@ -1318,10 +1322,16 @@ static void lcd_control_menu() {
   // Helpers for editing PID Ki & Kd values
   // grab the PID value out of the temp variable; scale it; then update the PID driver
   void copy_and_scalePID_i(int e) {
+    #if DISABLED(PID_PARAMS_PER_EXTRUDER)
+      UNUSED(e);
+    #endif
     PID_PARAM(Ki, e) = scalePID_i(raw_Ki);
     updatePID();
   }
   void copy_and_scalePID_d(int e) {
+    #if DISABLED(PID_PARAMS_PER_EXTRUDER)
+      UNUSED(e);
+    #endif
     PID_PARAM(Kd, e) = scalePID_d(raw_Kd);
     updatePID();
   }
@@ -1892,18 +1902,20 @@ static void menu_action_function(menuFunc_t func) { (*func)(); }
 #if ENABLED(SDSUPPORT)
 
   static void menu_action_sdfile(const char* filename, char* longFilename) {
+    UNUSED(longFilename);
     card.openAndPrintFile(filename);
     lcd_return_to_status();
   }
 
   static void menu_action_sddirectory(const char* filename, char* longFilename) {
+    UNUSED(longFilename);
     card.chdir(filename);
     encoderPosition = 0;
   }
 
 #endif //SDSUPPORT
 
-static void menu_action_setting_edit_bool(const char* pstr, bool* ptr) { *ptr = !(*ptr); }
+static void menu_action_setting_edit_bool(const char* pstr, bool* ptr) {UNUSED(pstr); *ptr = !(*ptr); }
 static void menu_action_setting_edit_callback_bool(const char* pstr, bool* ptr, menuFunc_t callback) {
   menu_action_setting_edit_bool(pstr, ptr);
   (*callback)();
@@ -2203,6 +2215,10 @@ void lcd_ignore_click(bool b) {
 }
 
 void lcd_finishstatus(bool persist=false) {
+  #if !(ENABLED(LCD_PROGRESS_BAR) && (PROGRESS_MSG_EXPIRE > 0))
+    UNUSED(persist);
+  #endif
+
   #if ENABLED(LCD_PROGRESS_BAR)
     progress_bar_ms = millis();
     #if PROGRESS_MSG_EXPIRE > 0
diff --git a/Marlin/ultralcd_implementation_hitachi_HD44780.h b/Marlin/ultralcd_implementation_hitachi_HD44780.h
index d8c11522f..6fdee2a66 100644
--- a/Marlin/ultralcd_implementation_hitachi_HD44780.h
+++ b/Marlin/ultralcd_implementation_hitachi_HD44780.h
@@ -873,6 +873,7 @@ void lcd_implementation_drawedit(const char* pstr, const char* value) {
 #if ENABLED(SDSUPPORT)
 
   static void lcd_implementation_drawmenu_sd(bool sel, uint8_t row, const char* pstr, const char* filename, char* longFilename, uint8_t concat, char post_char) {
+    UNUSED(pstr);
     char c;
     uint8_t n = LCD_WIDTH - concat;
     lcd.setCursor(0, row);