diff --git a/holidays/countries/greece.py b/holidays/countries/greece.py
index ee3d08710..235ecb8f3 100644
--- a/holidays/countries/greece.py
+++ b/holidays/countries/greece.py
@@ -14,7 +14,11 @@
 from holidays.calendars.julian_revised import JULIAN_REVISED_CALENDAR
 from holidays.constants import HALF_DAY, PUBLIC
 from holidays.groups import ChristianHolidays, InternationalHolidays
-from holidays.observed_holiday_base import ObservedHolidayBase, SAT_SUN_TO_NEXT_WORKDAY
+from holidays.observed_holiday_base import (
+    ObservedHolidayBase,
+    MON_TO_NEXT_TUE,
+    SAT_SUN_TO_NEXT_WORKDAY,
+)
 
 
 class Greece(ObservedHolidayBase, ChristianHolidays, InternationalHolidays):
@@ -36,6 +40,7 @@ def __init__(self, *args, **kwargs):
         ChristianHolidays.__init__(self, JULIAN_REVISED_CALENDAR)
         InternationalHolidays.__init__(self)
         kwargs.setdefault("observed_rule", SAT_SUN_TO_NEXT_WORKDAY)
+        kwargs.setdefault("observed_since", 2017)
         super().__init__(*args, **kwargs)
 
     def _populate_public_holidays(self):
@@ -45,7 +50,7 @@ def _populate_public_holidays(self):
         # Epiphany.
         self._add_epiphany_day(tr("Θεοφάνεια"))
 
-        # Clean Monday.
+        # Green Monday.
         self._add_ash_monday(tr("Καθαρά Δευτέρα"))
 
         # Independence Day.
@@ -55,13 +60,16 @@ def _populate_public_holidays(self):
         self._add_good_friday(tr("Μεγάλη Παρασκευή"))
 
         # Easter Monday.
-        self._add_easter_monday(tr("Δευτέρα του Πάσχα"))
+        easter_monday = self._add_easter_monday(tr("Δευτέρα του Πάσχα"))
 
-        # Monday of the Holy Spirit.
+        # Whit Monday.
         self._add_whit_monday(tr("Δευτέρα του Αγίου Πνεύματος"))
 
-        # Labour Day.
-        self._add_observed(self._add_labor_day(self.tr("Εργατική Πρωτομαγιά")))
+        self._add_observed(
+            # Labor Day.
+            may_1 := self._add_labor_day(self.tr("Εργατική Πρωτομαγιά")),
+            rule=MON_TO_NEXT_TUE if may_1 == easter_monday else SAT_SUN_TO_NEXT_WORKDAY,
+        )
 
         # Dormition of the Mother of God.
         self._add_assumption_of_mary_day(tr("Κοίμηση της Θεοτόκου"))
diff --git a/holidays/locale/el/LC_MESSAGES/GR.po b/holidays/locale/el/LC_MESSAGES/GR.po
index e53c504db..53577458a 100644
--- a/holidays/locale/el/LC_MESSAGES/GR.po
+++ b/holidays/locale/el/LC_MESSAGES/GR.po
@@ -24,7 +24,7 @@ msgstr ""
 msgid "Θεοφάνεια"
 msgstr ""
 
-#. Clean Monday.
+#. Green Monday.
 msgid "Καθαρά Δευτέρα"
 msgstr ""
 
@@ -40,11 +40,11 @@ msgstr ""
 msgid "Δευτέρα του Πάσχα"
 msgstr ""
 
-#. Monday of the Holy Spirit.
+#. Whit Monday.
 msgid "Δευτέρα του Αγίου Πνεύματος"
 msgstr ""
 
-#. Labour Day.
+#. Labor Day.
 msgid "Εργατική Πρωτομαγιά"
 msgstr ""
 
diff --git a/holidays/locale/en_US/LC_MESSAGES/GR.po b/holidays/locale/en_US/LC_MESSAGES/GR.po
index 6ac99caa9..6224ea9ba 100644
--- a/holidays/locale/en_US/LC_MESSAGES/GR.po
+++ b/holidays/locale/en_US/LC_MESSAGES/GR.po
@@ -24,9 +24,9 @@ msgstr "New Year's Day"
 msgid "Θεοφάνεια"
 msgstr "Epiphany"
 
-#. Clean Monday.
+#. Green Monday.
 msgid "Καθαρά Δευτέρα"
-msgstr "Clean Monday"
+msgstr "Green Monday"
 
 #. Independence Day.
 msgid "Εικοστή Πέμπτη Μαρτίου"
@@ -40,11 +40,11 @@ msgstr "Good Friday"
 msgid "Δευτέρα του Πάσχα"
 msgstr "Easter Monday"
 
-#. Monday of the Holy Spirit.
+#. Whit Monday.
 msgid "Δευτέρα του Αγίου Πνεύματος"
-msgstr "Easter Monday"
+msgstr "Whit Monday"
 
-#. Labour Day.
+#. Labor Day.
 msgid "Εργατική Πρωτομαγιά"
 msgstr "Labor Day"
 
diff --git a/holidays/locale/uk/LC_MESSAGES/GR.po b/holidays/locale/uk/LC_MESSAGES/GR.po
index 0599de088..a0bea19c1 100644
--- a/holidays/locale/uk/LC_MESSAGES/GR.po
+++ b/holidays/locale/uk/LC_MESSAGES/GR.po
@@ -24,7 +24,7 @@ msgstr "Новий рік"
 msgid "Θεοφάνεια"
 msgstr "Богоявлення"
 
-#. Clean Monday.
+#. Green Monday.
 msgid "Καθαρά Δευτέρα"
 msgstr "Чистий понеділок"
 
@@ -40,11 +40,11 @@ msgstr "Страсна пʼятниця"
 msgid "Δευτέρα του Πάσχα"
 msgstr "Великодній понеділок"
 
-#. Monday of the Holy Spirit.
+#. Whit Monday.
 msgid "Δευτέρα του Αγίου Πνεύματος"
 msgstr "День Святого Духа"
 
-#. Labour Day.
+#. Labor Day.
 msgid "Εργατική Πρωτομαγιά"
 msgstr "День праці"
 
diff --git a/snapshots/countries/GR_COMMON.json b/snapshots/countries/GR_COMMON.json
index 886c44b08..bdc68a976 100644
--- a/snapshots/countries/GR_COMMON.json
+++ b/snapshots/countries/GR_COMMON.json
@@ -62,7 +62,6 @@
     "1954-04-23": "Good Friday",
     "1954-04-26": "Easter Monday",
     "1954-05-01": "Labor Day",
-    "1954-05-03": "Labor Day (observed)",
     "1954-06-14": "Easter Monday",
     "1954-08-15": "Dormition of the Mother of God",
     "1954-10-28": "Ochi Day",
@@ -77,7 +76,6 @@
     "1955-04-15": "Good Friday",
     "1955-04-18": "Easter Monday",
     "1955-05-01": "Labor Day",
-    "1955-05-02": "Labor Day (observed)",
     "1955-06-06": "Easter Monday",
     "1955-08-15": "Dormition of the Mother of God",
     "1955-10-28": "Ochi Day",
@@ -147,7 +145,6 @@
     "1960-04-15": "Good Friday",
     "1960-04-18": "Easter Monday",
     "1960-05-01": "Labor Day",
-    "1960-05-02": "Labor Day (observed)",
     "1960-06-06": "Easter Monday",
     "1960-08-15": "Dormition of the Mother of God",
     "1960-10-28": "Ochi Day",
@@ -217,7 +214,6 @@
     "1965-04-23": "Good Friday",
     "1965-04-26": "Easter Monday",
     "1965-05-01": "Labor Day",
-    "1965-05-03": "Labor Day (observed)",
     "1965-06-14": "Easter Monday",
     "1965-08-15": "Dormition of the Mother of God",
     "1965-10-28": "Ochi Day",
@@ -232,7 +228,6 @@
     "1966-04-08": "Good Friday",
     "1966-04-11": "Easter Monday",
     "1966-05-01": "Labor Day",
-    "1966-05-02": "Labor Day (observed)",
     "1966-05-30": "Easter Monday",
     "1966-08-15": "Dormition of the Mother of God",
     "1966-10-28": "Ochi Day",
@@ -302,7 +297,6 @@
     "1971-04-16": "Good Friday",
     "1971-04-19": "Easter Monday",
     "1971-05-01": "Labor Day",
-    "1971-05-03": "Labor Day (observed)",
     "1971-06-07": "Easter Monday",
     "1971-08-15": "Dormition of the Mother of God",
     "1971-10-28": "Ochi Day",
@@ -373,7 +367,6 @@
     "1976-04-23": "Good Friday",
     "1976-04-26": "Easter Monday",
     "1976-05-01": "Labor Day",
-    "1976-05-03": "Labor Day (observed)",
     "1976-06-14": "Easter Monday",
     "1976-08-15": "Dormition of the Mother of God",
     "1976-10-28": "Ochi Day",
@@ -388,7 +381,6 @@
     "1977-04-08": "Good Friday",
     "1977-04-11": "Easter Monday",
     "1977-05-01": "Labor Day",
-    "1977-05-02": "Labor Day (observed)",
     "1977-05-30": "Easter Monday",
     "1977-08-15": "Dormition of the Mother of God",
     "1977-10-28": "Ochi Day",
@@ -458,7 +450,6 @@
     "1982-04-16": "Good Friday",
     "1982-04-19": "Easter Monday",
     "1982-05-01": "Labor Day",
-    "1982-05-03": "Labor Day (observed)",
     "1982-06-07": "Easter Monday",
     "1982-08-15": "Dormition of the Mother of God",
     "1982-10-28": "Ochi Day",
@@ -471,7 +462,6 @@
     "1983-03-21": "Clean Monday",
     "1983-03-25": "Independence Day",
     "1983-05-01": "Labor Day",
-    "1983-05-02": "Labor Day (observed)",
     "1983-05-06": "Good Friday",
     "1983-05-09": "Easter Monday",
     "1983-06-27": "Easter Monday",
@@ -544,7 +534,6 @@
     "1988-04-08": "Good Friday",
     "1988-04-11": "Easter Monday",
     "1988-05-01": "Labor Day",
-    "1988-05-02": "Labor Day (observed)",
     "1988-05-30": "Easter Monday",
     "1988-08-15": "Dormition of the Mother of God",
     "1988-10-28": "Ochi Day",
@@ -614,7 +603,6 @@
     "1993-04-16": "Good Friday",
     "1993-04-19": "Easter Monday",
     "1993-05-01": "Labor Day",
-    "1993-05-03": "Labor Day (observed)",
     "1993-06-07": "Easter Monday",
     "1993-08-15": "Dormition of the Mother of God",
     "1993-10-28": "Ochi Day",
@@ -629,7 +617,6 @@
     "1994-04-29": "Good Friday",
     "1994-05-01": "Labor Day",
     "1994-05-02": "Easter Monday",
-    "1994-05-03": "Labor Day (observed)",
     "1994-06-20": "Easter Monday",
     "1994-08-15": "Dormition of the Mother of God",
     "1994-10-28": "Ochi Day",
@@ -700,7 +687,6 @@
     "1999-04-09": "Good Friday",
     "1999-04-12": "Easter Monday",
     "1999-05-01": "Labor Day",
-    "1999-05-03": "Labor Day (observed)",
     "1999-05-31": "Easter Monday",
     "1999-08-15": "Dormition of the Mother of God",
     "1999-10-28": "Ochi Day",
@@ -770,7 +756,6 @@
     "2004-04-09": "Good Friday",
     "2004-04-12": "Easter Monday",
     "2004-05-01": "Labor Day",
-    "2004-05-03": "Labor Day (observed)",
     "2004-05-31": "Easter Monday",
     "2004-08-15": "Dormition of the Mother of God",
     "2004-10-28": "Ochi Day",
@@ -785,7 +770,6 @@
     "2005-04-29": "Good Friday",
     "2005-05-01": "Labor Day",
     "2005-05-02": "Easter Monday",
-    "2005-05-03": "Labor Day (observed)",
     "2005-06-20": "Easter Monday",
     "2005-08-15": "Dormition of the Mother of God",
     "2005-10-28": "Ochi Day",
@@ -856,7 +840,6 @@
     "2010-04-02": "Good Friday",
     "2010-04-05": "Easter Monday",
     "2010-05-01": "Labor Day",
-    "2010-05-03": "Labor Day (observed)",
     "2010-05-24": "Easter Monday",
     "2010-08-15": "Dormition of the Mother of God",
     "2010-10-28": "Ochi Day",
@@ -871,7 +854,6 @@
     "2011-04-22": "Good Friday",
     "2011-04-25": "Easter Monday",
     "2011-05-01": "Labor Day",
-    "2011-05-02": "Labor Day (observed)",
     "2011-06-13": "Easter Monday",
     "2011-08-15": "Dormition of the Mother of God",
     "2011-10-28": "Ochi Day",
@@ -942,7 +924,6 @@
     "2016-04-29": "Good Friday",
     "2016-05-01": "Labor Day",
     "2016-05-02": "Easter Monday",
-    "2016-05-03": "Labor Day (observed)",
     "2016-06-20": "Easter Monday",
     "2016-08-15": "Dormition of the Mother of God",
     "2016-10-28": "Ochi Day",
diff --git a/tests/countries/test_greece.py b/tests/countries/test_greece.py
index 0d1ab5f7f..a60b29c26 100644
--- a/tests/countries/test_greece.py
+++ b/tests/countries/test_greece.py
@@ -74,7 +74,7 @@ def test_easter_monday(self):
             "2024-05-06",
         )
 
-    def test_monday_of_the_holy_spirit(self):
+    def test_whit_monday(self):
         self.assertHolidayName(
             "Δευτέρα του Αγίου Πνεύματος",
             "2018-05-28",
@@ -86,19 +86,17 @@ def test_monday_of_the_holy_spirit(self):
             "2024-06-24",
         )
 
-    def test_labour_day_observed(self):
+    def test_labor_day_observed(self):
         name_observed = "Εργατική Πρωτομαγιά (παρατηρήθηκε)"
         dt = (
-            "2011-05-02",
-            "2016-05-03",
             "2021-05-04",
             "2022-05-02",
         )
         self.assertHolidayName(name_observed, dt)
         self.assertNoNonObservedHoliday(dt)
-        self.assertNoHolidayName(name_observed, 2017, 2018, 2019, 2020, 2023)
+        self.assertNoHolidayName(name_observed, range(2000, 2021), 2023)
 
-    def test_hal_day_2022(self):
+    def test_half_day_2022(self):
         self.assertHolidays(
             Greece(categories=HALF_DAY, years=2022),
             ("2022-12-24", "Παραμονή Χριστουγέννων"),
@@ -133,13 +131,13 @@ def test_l10n_en_us(self):
             "en_US",
             ("2022-01-01", "New Year's Day"),
             ("2022-01-06", "Epiphany"),
-            ("2022-03-07", "Clean Monday"),
+            ("2022-03-07", "Green Monday"),
             ("2022-03-25", "Independence Day"),
             ("2022-04-22", "Good Friday"),
             ("2022-04-25", "Easter Monday"),
             ("2022-05-01", "Labor Day"),
             ("2022-05-02", "Labor Day (observed)"),
-            ("2022-06-13", "Easter Monday"),
+            ("2022-06-13", "Whit Monday"),
             ("2022-08-15", "Dormition of the Mother of God"),
             ("2022-10-28", "Ochi Day"),
             ("2022-12-24", "Christmas Eve"),