diff --git a/marshmallow/decorators.py b/marshmallow/decorators.py
index 8b6df0df..cd850fc0 100644
--- a/marshmallow/decorators.py
+++ b/marshmallow/decorators.py
@@ -107,6 +107,9 @@ def post_dump(fn=None, pass_many=False, pass_original=False):
     By default, receives a single object at a time, transparently handling the ``many``
     argument passed to the Schema. If ``pass_many=True``, the raw data
     (which may be a collection) and the value for ``many`` is passed.
+
+    If ``pass_original=True``, the original data (before serializing) will be passed as
+    an additional argument to the method.
     """
     return tag_processor(POST_DUMP, fn, pass_many, pass_original=pass_original)
 
@@ -129,6 +132,9 @@ def post_load(fn=None, pass_many=False, pass_original=False):
     By default, receives a single datum at a time, transparently handling the ``many``
     argument passed to the Schema. If ``pass_many=True``, the raw data
     (which may be a collection) and the value for ``many`` is passed.
+
+    If ``pass_original=True``, the original data (before deserializing) will be passed as
+    an additional argument to the method.
     """
     return tag_processor(POST_LOAD, fn, pass_many, pass_original=pass_original)
 
diff --git a/marshmallow/schema.py b/marshmallow/schema.py
index 79bb8ee1..904c5322 100644
--- a/marshmallow/schema.py
+++ b/marshmallow/schema.py
@@ -869,8 +869,8 @@ class BaseSchema(base.SchemaABC):
                     data = utils.if_none(processor(data, many), data)
             elif many:
                 if pass_original:
-                    data = [utils.if_none(processor(item, original_data), item)
-                            for item in data]
+                    data = [utils.if_none(processor(item, original), item)
+                            for item, original in zip(data, original_data)]
                 else:
                     data = [utils.if_none(processor(item), item) for item in data]
             else:

post_dump is passing a list of objects as original object
Hi,

I think post_dump with pass_original=True should pass the original object related to the data serialized and not a list of objects which this object belongs to.

``` python
from marshmallow import fields, post_dump, Schema

class DeviceSchema(Schema):
    id = fields.String()

    @post_dump(pass_original=True)
    def __post_dump(self, data, obj):
        print(obj)  # <-- this is a list

devices = [dict(id=1), dict(id=2)]
DeviceSchema().dump(devices, many=True)
```

In the above example, the parameter `obj` is a list of devices rather than the device object itself.

What do you think?

diff --git a/tests/test_decorators.py b/tests/test_decorators.py
index 226e550f..41a2d44a 100644
--- a/tests/test_decorators.py
+++ b/tests/test_decorators.py
@@ -758,3 +758,80 @@ def test_decorator_error_handling_with_dump(decorator):
         schema.dump(object())
     assert exc.value.messages == {'foo': 'error'}
     schema.load({})
+
+
+class Nested(object):
+    def __init__(self, foo):
+        self.foo = foo
+
+
+class Example(object):
+    def __init__(self, nested):
+        self.nested = nested
+
+
+example = Example(nested=[Nested(x) for x in range(1)])
+
+
+@pytest.mark.parametrize(
+    "data,expected_data,expected_original_data",
+    (
+        [example, {"foo": 0}, example.nested[0]],
+    ),
+)
+def test_decorator_post_dump_with_nested_pass_original_and_pass_many(
+        data, expected_data, expected_original_data):
+
+    class NestedSchema(Schema):
+        foo = fields.Int(required=True)
+
+        @post_dump(pass_many=False, pass_original=True)
+        def check_pass_original_when_pass_many_false(self, data, original_data):
+            assert data == expected_data
+            assert original_data == expected_original_data
+            return data
+
+        @post_dump(pass_many=True, pass_original=True)
+        def check_pass_original_when_pass_many_true(self, data, many, original_data):
+            assert many is True
+            assert data == [expected_data]
+            assert original_data == [expected_original_data]
+            return data
+
+    class ExampleSchema(Schema):
+        nested = fields.Nested(NestedSchema, required=True, many=True)
+
+    schema = ExampleSchema()
+    assert schema.dump(data) == {"nested": [{"foo": 0}]}
+
+
+@pytest.mark.parametrize(
+    "data,expected_data,expected_original_data",
+    (
+        [{"nested": [{"foo": 0}]}, {"foo": 0}, {"foo": 0}],
+    ),
+)
+def test_decorator_post_load_with_nested_pass_original_and_pass_many(
+        data, expected_data, expected_original_data):
+
+    class NestedSchema(Schema):
+        foo = fields.Int(required=True)
+
+        @post_load(pass_many=False, pass_original=True)
+        def check_pass_original_when_pass_many_false(self, data, original_data):
+            assert data == expected_data
+            assert original_data == expected_original_data
+            return data
+
+        @post_load(pass_many=True, pass_original=True)
+        def check_pass_original_when_pass_many_true(self, data, many, original_data):
+            assert many is True
+            assert data == [expected_data]
+            assert original_data == [expected_original_data]
+            return data
+
+    class ExampleSchema(Schema):
+        nested = fields.Nested(NestedSchema, required=True, many=True)
+
+    schema = ExampleSchema()
+    assert schema.load(data) == data

pip install -e .[reco]
parse_log_pytest
requirements.txt
pytest pytest-cov pytest-xdist pytest-mock pytest-asyncio
3.9
dev-requirements.txt requirements.txt
pytest --no-header -rA --tb=line --color=no -p no:cacheprovider -W ignore::DeprecationWarning
attrs==25.3.0
coverage==7.8.0
distlib==0.3.9
exceptiongroup==1.2.2
execnet==2.1.1
filelock==3.18.0
flake8==3.5.0
iniconfig==2.1.0
invoke==0.22.0
-e git+https://github.com/marshmallow-code/marshmallow.git@a867533d53ddbe8cb0ff63c1dc3ca53337ba525c#egg=marshmallow
mccabe==0.6.1
packaging==24.2
platformdirs==4.3.7
pluggy==1.5.0
py==1.11.0
pycodestyle==2.3.1
pyflakes==1.6.0
pytest==8.3.5
pytest-asyncio==0.26.0
pytest-cov==6.0.0
pytest-mock==3.14.0
pytest-xdist==3.6.1
python-dateutil==2.6.1
pytz==2017.3
simplejson==3.13.2
six==1.17.0
toml==0.10.2
tomli==2.2.1
tox==3.12.1
typing_extensions==4.13.0
virtualenv==20.29.3

name: marshmallow
channels:
  - defaults
  - https://repo.anaconda.com/pkgs/main
  - https://repo.anaconda.com/pkgs/r
  - conda-forge
dependencies:
  - _libgcc_mutex=0.1=main
  - _openmp_mutex=5.1=1_gnu
  - ca-certificates=2025.2.25=h06a4308_0
  - ld_impl_linux-64=2.40=h12ee557_0
  - libffi=3.4.4=h6a678d5_1
  - libgcc-ng=11.2.0=h1234567_1
  - libgomp=11.2.0=h1234567_1
  - libstdcxx-ng=11.2.0=h1234567_1
  - ncurses=6.4=h6a678d5_0
  - openssl=3.0.16=h5eee18b_0
  - pip=25.0=py39h06a4308_0
  - python=3.9.21=he870216_1
  - readline=8.2=h5eee18b_0
  - setuptools=75.8.0=py39h06a4308_0
  - sqlite=3.45.3=h5eee18b_0
  - tk=8.6.14=h39e8969_0
  - tzdata=2025a=h04d1e81_0
  - wheel=0.45.1=py39h06a4308_0
  - xz=5.6.4=h5eee18b_1
  - zlib=1.2.13=h5eee18b_1
  - pip:
      - attrs==25.3.0
      - coverage==7.8.0
      - distlib==0.3.9
      - exceptiongroup==1.2.2
      - execnet==2.1.1
      - filelock==3.18.0
      - flake8==3.5.0
      - iniconfig==2.1.0
      - invoke==0.22.0
      - mccabe==0.6.1
      - packaging==24.2
      - platformdirs==4.3.7
      - pluggy==1.5.0
      - py==1.11.0
      - pycodestyle==2.3.1
      - pyflakes==1.6.0
      - pytest==8.3.5
      - pytest-asyncio==0.26.0
      - pytest-cov==6.0.0
      - pytest-mock==3.14.0
      - pytest-xdist==3.6.1
      - python-dateutil==2.6.1
      - pytz==2017.3
      - simplejson==3.13.2
      - six==1.17.0
      - toml==0.10.2
      - tomli==2.2.1
      - tox==3.12.1
      - typing-extensions==4.13.0
      - virtualenv==20.29.3
prefix: /opt/conda/envs/marshmallow

tests/test_decorators.py::test_decorator_post_dump_with_nested_pass_original_and_pass_many[data0-expected_data0-expected_original_data0] tests/test_decorators.py::test_decorator_post_load_with_nested_pass_original_and_pass_many[data0-expected_data0-expected_original_data0]
tests/test_decorators.py::test_decorated_processors tests/test_decorators.py::TestPassOriginal::test_pass_original_single_no_mutation tests/test_decorators.py::TestPassOriginal::test_pass_original_single_with_mutation tests/test_decorators.py::TestPassOriginal::test_pass_original_many tests/test_decorators.py::test_decorated_processor_inheritance tests/test_decorators.py::test_pre_dump_is_invoked_before_implicit_field_generation tests/test_decorators.py::TestValidatesDecorator::test_validates tests/test_decorators.py::TestValidatesDecorator::test_validates_with_attribute tests/test_decorators.py::TestValidatesDecorator::test_validates_decorator tests/test_decorators.py::TestValidatesDecorator::test_field_not_present tests/test_decorators.py::TestValidatesDecorator::test_precedence tests/test_decorators.py::TestValidatesSchemaDecorator::test_validator_nested_many tests/test_decorators.py::TestValidatesSchemaDecorator::test_validator_nested_many_pass_original_and_pass_many[True-expected_data0-expected_original_data0-data0] tests/test_decorators.py::TestValidatesSchemaDecorator::test_validator_nested_many_pass_original_and_pass_many[False-expected_data1-expected_original_data1-data0] tests/test_decorators.py::TestValidatesSchemaDecorator::test_decorated_validators tests/test_decorators.py::TestValidatesSchemaDecorator::test_multiple_validators tests/test_decorators.py::TestValidatesSchemaDecorator::test_passing_original_data tests/test_decorators.py::TestValidatesSchemaDecorator::test_allow_arbitrary_field_names_in_error tests/test_decorators.py::TestValidatesSchemaDecorator::test_skip_on_field_errors tests/test_decorators.py::test_decorator_error_handling tests/test_decorators.py::test_decorator_error_handling_with_load[pre_load] tests/test_decorators.py::test_decorator_error_handling_with_load[post_load] tests/test_decorators.py::test_decorator_error_handling_with_dump[pre_dump] tests/test_decorators.py::test_decorator_error_handling_with_dump[post_dump]
marshmallow/schema.py marshmallow/decorators.py
marshmallow/schema.py marshmallow/decorators.py