diff --git a/docs/1-essentials/03-database.md b/docs/1-essentials/03-database.md
index 793273d15..fdaa0dd38 100644
--- a/docs/1-essentials/03-database.md
+++ b/docs/1-essentials/03-database.md
@@ -447,6 +447,57 @@ final class Book
 }
 ```
 
+### Hidden properties
+
+Sensitive properties can be marked with the {b`#[Tempest\Mapper\Hidden]`} attribute to exclude them from SELECT queries. This is useful for properties like passwords, API keys, or other sensitive data that should not be fetched or exposed by default.
+
+```php
+use Tempest\Database\IsDatabaseModel;
+use Tempest\Mapper\Hidden;
+
+final class User
+{
+    use IsDatabaseModel;
+
+    public string $email;
+
+    #[Hidden]
+    public string $password;
+
+    #[Hidden]
+    public ?string $apiKey = null;
+}
+```
+
+Hidden properties are still included in INSERT and UPDATE queries, allowing them to be persisted to the database.
+
+To explicitly include hidden fields in a query, use the `include()` method on the query builder:
+
+```php
+// Password is not included in the query
+$user = User::select()->where('email', $email)->first();
+
+// Password is explicitly included
+$user = User::select()
+    ->include('password')
+    ->where('email', $email)
+    ->first();
+
+// Multiple hidden fields can be included
+$user = User::select()
+    ->include('password', 'apiKey')
+    ->where('email', $email)
+    ->first();
+```
+
+:::info
+Unlike {b`#[Virtual]`} which marks computed properties that don't exist in the database, {b`#[Hidden]`} is for real database columns that should be protected from accidental exposure.
+:::
+
+:::info
+The {b`#[Hidden]`} attribute also excludes properties from serialization. See the [mapper documentation](../2-features/01-mapper.md#hiding-properties-from-serialization) for more information.
+:::
+
 ### The `IsDatabaseModel` trait
 
 The {b`Tempest\Database\IsDatabaseModel`} trait provides an active record pattern. This trait enables database interaction via static methods on the model class itself.
diff --git a/docs/2-features/01-mapper.md b/docs/2-features/01-mapper.md
index 342165552..b33967c1a 100644
--- a/docs/2-features/01-mapper.md
+++ b/docs/2-features/01-mapper.md
@@ -71,6 +71,40 @@ $array = map($book)->toArray();
 $json = map($book)->toJson();
 ```
 
+### Hiding properties from serialization
+
+Properties marked with the {b`#[Tempest\Mapper\Hidden]`} attribute are excluded from serialization. This is useful for sensitive data like passwords or API keys that should never be exposed in arrays or JSON responses.
+
+```php
+use Tempest\Mapper\Hidden;
+
+final class User
+{
+    public string $email;
+
+    #[Hidden]
+    public string $password;
+}
+```
+
+When serializing, hidden properties are automatically excluded:
+
+```php
+$user = new User();
+$user->email = 'user@example.com';
+$user->password = 'secret';
+
+$array = map($user)->toArray();
+// ['email' => 'user@example.com']
+
+$json = map($user)->toJson();
+// {"email":"user@example.com"}
+```
+
+:::info
+The {b`#[Hidden]`} attribute also excludes properties from database SELECT queries. See the [database documentation](../1-essentials/03-database.md#hidden-properties) for more information.
+:::
+
 ### Overriding field names
 
 When mapping from an array to an object, Tempest uses the property names of the target class to map the data. If a property name doesn't match a key in the source array, use the {b`#[Tempest\Mapper\MapFrom]`} attribute to specify the source key to map to the property.
diff --git a/packages/database/src/Builder/ModelInspector.php b/packages/database/src/Builder/ModelInspector.php
index 7b349e3a8..d39dab76d 100644
--- a/packages/database/src/Builder/ModelInspector.php
+++ b/packages/database/src/Builder/ModelInspector.php
@@ -13,6 +13,7 @@
 use Tempest\Database\Table;
 use Tempest\Database\Uuid;
 use Tempest\Database\Virtual;
+use Tempest\Mapper\Hidden;
 use Tempest\Mapper\SerializeAs;
 use Tempest\Mapper\SerializeWith;
 use Tempest\Reflection\ClassReflector;
@@ -397,6 +398,10 @@ public function getSelectFields(): ImmutableArray
                 continue;
             }
 
+            if ($property->hasAttribute(Hidden::class)) {
+                continue;
+            }
+
             if ($property->getType()->equals(PrimaryKey::class)) {
                 continue;
             }
diff --git a/packages/database/src/Builder/QueryBuilders/QueryBuilder.php b/packages/database/src/Builder/QueryBuilders/QueryBuilder.php
index 9394d6f87..1acd8c54f 100644
--- a/packages/database/src/Builder/QueryBuilders/QueryBuilder.php
+++ b/packages/database/src/Builder/QueryBuilders/QueryBuilder.php
@@ -40,7 +40,7 @@ public function select(string ...$columns): SelectQueryBuilder
     {
         return new SelectQueryBuilder(
             model: $this->model,
-            fields: $columns !== [] ? arr($columns) : null,
+            fields: $columns !== [] ? arr($columns)->unique() : null,
         );
     }
 
diff --git a/packages/database/src/Builder/QueryBuilders/SelectQueryBuilder.php b/packages/database/src/Builder/QueryBuilders/SelectQueryBuilder.php
index b348653c5..202d91afa 100644
--- a/packages/database/src/Builder/QueryBuilders/SelectQueryBuilder.php
+++ b/packages/database/src/Builder/QueryBuilders/SelectQueryBuilder.php
@@ -314,6 +314,28 @@ public function with(string ...$relations): self
         return $this;
     }
 
+    /**
+     * Includes additional fields in the query. Useful for including hidden fields.
+     *
+     * @return self<TModel>
+     */
+    public function include(string ...$fields): self
+    {
+        $tableName = $this->model->getTableName();
+        $existingFields = $this->model->getSelectFields()->toArray();
+
+        foreach ($fields as $field) {
+            if (in_array($field, $existingFields, true)) {
+                continue;
+            }
+
+            $existingFields[] = $field;
+            $this->select->fields[] = new FieldStatement("{$tableName}.{$field}")->withAlias();
+        }
+
+        return $this;
+    }
+
     /**
      * Adds a raw SQL statement to the query.
      *
diff --git a/packages/mapper/src/Hidden.php b/packages/mapper/src/Hidden.php
new file mode 100644
index 000000000..9c9e94f05
--- /dev/null
+++ b/packages/mapper/src/Hidden.php
@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Tempest\Mapper;
+
+use Attribute;
+
+/**
+ * Hidden properties are excluded from SELECT queries and serialization.
+ */
+#[Attribute(Attribute::TARGET_PROPERTY)]
+final readonly class Hidden
+{
+}
diff --git a/packages/mapper/src/Mappers/ObjectToArrayMapper.php b/packages/mapper/src/Mappers/ObjectToArrayMapper.php
index ef68537f1..f72f411d2 100644
--- a/packages/mapper/src/Mappers/ObjectToArrayMapper.php
+++ b/packages/mapper/src/Mappers/ObjectToArrayMapper.php
@@ -6,6 +6,7 @@
 
 use JsonSerializable;
 use Tempest\Mapper\Context;
+use Tempest\Mapper\Hidden;
 use Tempest\Mapper\Mapper;
 use Tempest\Mapper\MapTo;
 use Tempest\Mapper\SerializerFactory;
@@ -38,6 +39,10 @@ public function map(mixed $from, mixed $to): mixed
             $mappedProperties = [];
 
             foreach ($class->getPublicProperties() as $property) {
+                if ($property->hasAttribute(Hidden::class)) {
+                    continue;
+                }
+
                 $propertyName = $this->resolvePropertyName($property);
                 $propertyValue = $this->resolvePropertyValue($property, $from);
                 $mappedProperties[$propertyName] = $propertyValue;
diff --git a/tests/Integration/Database/ModelInspector/HiddenTest.php b/tests/Integration/Database/ModelInspector/HiddenTest.php
new file mode 100644
index 000000000..80034e65c
--- /dev/null
+++ b/tests/Integration/Database/ModelInspector/HiddenTest.php
@@ -0,0 +1,153 @@
+<?php
+
+namespace Tests\Tempest\Integration\Database\ModelInspector;
+
+use PHPUnit\Framework\Attributes\Test;
+use Tempest\Database\IsDatabaseModel;
+use Tempest\Database\PrimaryKey;
+use Tempest\Database\Table;
+use Tempest\Mapper\Hidden;
+use Tests\Tempest\Integration\FrameworkIntegrationTestCase;
+
+use function Tempest\Database\inspect;
+use function Tempest\Database\query;
+use function Tempest\Mapper\map;
+
+final class HiddenTest extends FrameworkIntegrationTestCase
+{
+    #[Test]
+    public function hidden_property_is_excluded_from_select_fields(): void
+    {
+        $model = inspect(HiddenTestModel::class);
+        $selectFields = $model->getSelectFields();
+
+        $this->assertContains('id', $selectFields->toArray());
+        $this->assertContains('name', $selectFields->toArray());
+        $this->assertNotContains('password', $selectFields->toArray());
+        $this->assertNotContains('secret', $selectFields->toArray());
+    }
+
+    #[Test]
+    public function hidden_property_is_included_in_property_values(): void
+    {
+        $instance = new HiddenTestModel();
+        $instance->id = new PrimaryKey(1);
+        $instance->name = 'John';
+        $instance->password = 'secret123'; // @mago-expect lint:no-literal-password
+        $instance->secret = 'my-secret'; // @mago-expect lint:no-literal-password
+
+        $model = inspect($instance);
+        $propertyValues = $model->getPropertyValues();
+
+        $this->assertArrayHasKey('name', $propertyValues);
+        $this->assertArrayHasKey('password', $propertyValues);
+        $this->assertArrayHasKey('secret', $propertyValues);
+        $this->assertSame('John', $propertyValues['name']);
+        $this->assertSame('secret123', $propertyValues['password']);
+        $this->assertSame('my-secret', $propertyValues['secret']);
+    }
+
+    #[Test]
+    public function hidden_property_is_excluded_from_serialization(): void
+    {
+        $object = new HiddenTestModel();
+        $object->id = new PrimaryKey(1);
+        $object->name = 'John';
+        $object->password = 'secret123'; // @mago-expect lint:no-literal-password
+        $object->secret = 'my-secret'; // @mago-expect lint:no-literal-password
+
+        $array = map($object)->toArray();
+
+        $this->assertArrayHasKey('id', $array);
+        $this->assertArrayHasKey('name', $array);
+        $this->assertArrayNotHasKey('password', $array);
+        $this->assertArrayNotHasKey('secret', $array);
+    }
+
+    #[Test]
+    public function hidden_property_is_excluded_from_json_serialization(): void
+    {
+        $object = new HiddenTestModel();
+        $object->id = new PrimaryKey(1);
+        $object->name = 'John';
+        $object->password = 'secret123'; // @mago-expect lint:no-literal-password
+        $object->secret = 'my-secret'; // @mago-expect lint:no-literal-password
+
+        $json = map($object)->toJson();
+
+        $this->assertStringContainsString('"name":"John"', $json);
+        $this->assertStringNotContainsString('password', $json);
+        $this->assertStringNotContainsString('secret', $json);
+    }
+
+    #[Test]
+    public function include_adds_hidden_fields_to_query(): void
+    {
+        $sql = HiddenTestModel::select()->compile()->toString();
+
+        $this->assertStringNotContainsString('password', $sql);
+        $this->assertStringNotContainsString('secret', $sql);
+
+        $sql = HiddenTestModel::select()
+            ->include('password')
+            ->compile()
+            ->toString();
+
+        $this->assertStringContainsString('password', $sql);
+        $this->assertStringNotContainsString('secret', $sql);
+
+        $sql = HiddenTestModel::select()
+            ->include('password', 'secret')
+            ->compile()
+            ->toString();
+
+        $this->assertStringContainsString('password', $sql);
+        $this->assertStringContainsString('secret', $sql);
+    }
+
+    #[Test]
+    public function include_with_already_selected_field_is_ignored(): void
+    {
+        $sql = HiddenTestModel::select()
+            ->include('name')
+            ->compile()
+            ->toString();
+
+        $this->assertSame(2, substr_count($sql, 'name'));
+    }
+
+    #[Test]
+    public function include_with_duplicate_selected_field_is_filtered(): void
+    {
+        $sql = HiddenTestModel::select()
+            ->include('password', 'password')
+            ->compile()
+            ->toString();
+
+        $this->assertSame(2, substr_count($sql, 'password'));
+    }
+
+    #[Test]
+    public function select_with_duplicate_selected_field_is_filtered(): void
+    {
+        $sql = query(HiddenTestModel::class)->select('name', 'name')->include('name')->compile()->toString();
+
+        $this->assertSame(1, substr_count($sql, 'name'));
+    }
+}
+
+#[Table('hidden_test')]
+final class HiddenTestModel
+{
+    use IsDatabaseModel;
+
+    public PrimaryKey $id;
+
+    public string $name;
+
+    #[Hidden]
+    public string $password;
+
+    #[Hidden]
+    public string $secret;
+}