diff --git a/base_tier_validation/README.rst b/base_tier_validation/README.rst
index ef4b0875f..622914e05 100644
--- a/base_tier_validation/README.rst
+++ b/base_tier_validation/README.rst
@@ -70,6 +70,9 @@ To configure this module, you need to:
 
 **Note:**
 
+- With *Validated by: Any of specific users*, list the users under
+  *Reviewers*: any one of them can validate, like a member of a reviewer
+  group, without creating a group for them.
 - If check *Notify Reviewers on Creation*, all possible reviewers will
   be notified by email when this definition is triggered.
 - If check *Notify reviewers on reaching pending* if you want to send a
diff --git a/base_tier_validation/models/tier_definition.py b/base_tier_validation/models/tier_definition.py
index e9f3402b5..cec0f9430 100644
--- a/base_tier_validation/models/tier_definition.py
+++ b/base_tier_validation/models/tier_definition.py
@@ -36,6 +36,7 @@ def _get_tier_validation_model_names(self):
         default="individual",
         selection=[
             ("individual", "Specific user"),
+            ("users", "Any of specific users"),
             ("group", "Any user in a specific group"),
             ("field", "Field in related record"),
         ],
@@ -48,6 +49,16 @@ def _get_tier_validation_model_names(self):
     reviewer_group_id = fields.Many2one(
         comodel_name="res.groups", string="Reviewer group"
     )
+    reviewer_user_ids = fields.Many2many(
+        comodel_name="res.users",
+        relation="tier_definition_reviewer_user_rel",
+        column1="definition_id",
+        column2="user_id",
+        string="Reviewers",
+        domain="[('share', '=', False)]",
+        help="Any one of these users can validate, like a member of a reviewer "
+        "group, without having to create a group for them.",
+    )
     reviewer_field_id = fields.Many2one(
         comodel_name="ir.model.fields",
         string="Reviewer field",
@@ -122,14 +133,15 @@ def _get_tier_validation_model_names(self):
         "group can validate -- except the requester themselves. Without "
         "this flag, a requester who happens to be in the same group as "
         "the configured reviewers can auto-validate their own request. "
-        "Only meaningful for review_type='group'; the form hides this "
-        "field for the other review types.",
+        "Only meaningful when several users can review (a group or a list "
+        "of users); the form hides this field for the other review types.",
     )
 
     @api.onchange("review_type")
     def onchange_review_type(self):
         self.reviewer_id = None
         self.reviewer_group_id = None
+        self.reviewer_user_ids = False
 
     def _reviewers_without_model_access(self, model_name, users):
         """Return the subset of ``users`` that cannot read ``model_name``.
@@ -160,9 +172,19 @@ def _reviewers_to_check_for_access(self):
             return self.reviewer_id
         if self.review_type == "group":
             return self.reviewer_group_id.user_ids
+        if self.review_type == "users":
+            # In a form, the lines of an x2many are new records; check the
+            # users themselves.
+            return self.reviewer_user_ids._origin
         return self.env["res.users"]
 
-    @api.onchange("review_type", "reviewer_id", "reviewer_group_id", "model_id")
+    @api.onchange(
+        "review_type",
+        "reviewer_id",
+        "reviewer_group_id",
+        "reviewer_user_ids",
+        "model_id",
+    )
     def _onchange_warn_reviewer_access(self):
         """Advisory warning when an assigned reviewer cannot read the model.
 
diff --git a/base_tier_validation/models/tier_review.py b/base_tier_validation/models/tier_review.py
index 2b4cd2ffd..df96df4b4 100644
--- a/base_tier_validation/models/tier_review.py
+++ b/base_tier_validation/models/tier_review.py
@@ -39,6 +39,9 @@ class TierReview(models.Model):
     review_type = fields.Selection(related="definition_id.review_type")
     reviewer_id = fields.Many2one(related="definition_id.reviewer_id")
     reviewer_group_id = fields.Many2one(related="definition_id.reviewer_group_id")
+    reviewer_user_ids = fields.Many2many(
+        related="definition_id.reviewer_user_ids", string="Listed Reviewers"
+    )
     reviewer_field_id = fields.Many2one(related="definition_id.reviewer_field_id")
     reviewer_ids = fields.Many2many(
         string="Reviewers",
@@ -152,6 +155,8 @@ def _get_reviewer_fields(self):
             "reviewer_id",
             "reviewer_group_id",
             "reviewer_group_id.user_ids",
+            "review_type",
+            "reviewer_user_ids",
             "definition_id.exclude_requester",
             "requested_by",
         ]
@@ -178,7 +183,9 @@ def _compute_todo_by(self):
 
     def _get_reviewers(self):
         reviewers = self.env["res.users"]
-        if self.reviewer_id or self.reviewer_group_id.user_ids:
+        if self.review_type == "users":
+            reviewers = self.reviewer_user_ids
+        elif self.reviewer_id or self.reviewer_group_id.user_ids:
             reviewers = self.reviewer_id + self.reviewer_group_id.user_ids
         elif self.reviewer_field_id:
             resource = self.env[self.model].browse(self.res_id)
diff --git a/base_tier_validation/readme/CONFIGURE.md b/base_tier_validation/readme/CONFIGURE.md
index 4bd817e66..1fa346b8d 100644
--- a/base_tier_validation/readme/CONFIGURE.md
+++ b/base_tier_validation/readme/CONFIGURE.md
@@ -7,6 +7,9 @@ To configure this module, you need to:
 
 **Note:**
 
+- With *Validated by: Any of specific users*, list the users under
+  *Reviewers*: any one of them can validate, like a member of a reviewer
+  group, without creating a group for them.
 - If check *Notify Reviewers on Creation*, all possible reviewers will
   be notified by email when this definition is triggered.
 - If check *Notify reviewers on reaching pending* if you want to send a notification when pending status is reached.
diff --git a/base_tier_validation/readme/newsfragments/91.feature b/base_tier_validation/readme/newsfragments/91.feature
new file mode 100644
index 000000000..a407ac78d
--- /dev/null
+++ b/base_tier_validation/readme/newsfragments/91.feature
@@ -0,0 +1 @@
+New *Validated by* option *Any of specific users*: any one of the listed users can validate, without creating a group for them.
diff --git a/base_tier_validation/static/description/index.html b/base_tier_validation/static/description/index.html
index 2e9108df6..88604ea88 100644
--- a/base_tier_validation/static/description/index.html
+++ b/base_tier_validation/static/description/index.html
@@ -3,7 +3,7 @@
 <head>
 <meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
 <meta name="generator" content="Docutils: https://docutils.sourceforge.io/" />
-<title>Base Tier Validation</title>
+<title>README.rst</title>
 <style type="text/css">
 
 /*
@@ -438,6 +438,9 @@ <h2><a class="toc-backref" href="#toc-entry-1">Configuration</a></h2>
 </ol>
 <p><strong>Note:</strong></p>
 <ul class="simple">
+<li>With <em>Validated by: Any of specific users</em>, list the users under
+<em>Reviewers</em>: any one of them can validate, like a member of a reviewer
+group, without creating a group for them.</li>
 <li>If check <em>Notify Reviewers on Creation</em>, all possible reviewers will
 be notified by email when this definition is triggered.</li>
 <li>If check <em>Notify reviewers on reaching pending</em> if you want to send a
diff --git a/base_tier_validation/tests/__init__.py b/base_tier_validation/tests/__init__.py
index 9859e84ca..412e302f5 100644
--- a/base_tier_validation/tests/__init__.py
+++ b/base_tier_validation/tests/__init__.py
@@ -2,3 +2,4 @@
 
 from . import test_tier_validation
 from . import test_tier_validation_reminder
+from . import test_tier_validation_users
diff --git a/base_tier_validation/tests/test_tier_validation_users.py b/base_tier_validation/tests/test_tier_validation_users.py
new file mode 100644
index 000000000..0f50f621f
--- /dev/null
+++ b/base_tier_validation/tests/test_tier_validation_users.py
@@ -0,0 +1,56 @@
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+from odoo.tests import Form, new_test_user, tagged
+
+from .common import CommonTierValidation
+
+
+@tagged("post_install", "-at_install")
+class TierValidationAnyOfUsers(CommonTierValidation):
+    """Validated by "Any of specific users": a list of users, no group."""
+
+    def _setup_tier_definitions(self):
+        self.reviewer_a = new_test_user(self.env, login="reviewer_a", name="Anna")
+        self.reviewer_b = new_test_user(self.env, login="reviewer_b", name="Bert")
+        self.definition = self.tier_def_obj.create(
+            {
+                "model_id": self.tester_model.id,
+                "review_type": "users",
+                "reviewer_user_ids": [(6, 0, (self.reviewer_a | self.reviewer_b).ids)],
+                "definition_domain": "[('test_field', '>', 1.0)]",
+            }
+        )
+
+    def test_any_listed_user_validates(self):
+        record = self.test_model.create({"test_field": 2.0})
+        review = record.with_user(self.test_user_2).request_validation()
+        self.assertEqual(review.reviewer_ids, self.reviewer_a | self.reviewer_b)
+        self.assertEqual(review.todo_by, "Anna, Bert")
+        self.assertNotIn(review, self.test_user_1.review_ids)
+        record.with_user(self.reviewer_b).validate_tier()
+        self.assertEqual(review.status, "approved")
+        self.assertEqual(review.done_by, self.reviewer_b)
+        self.assertEqual(record.validation_status, "validated")
+
+    def test_changing_the_list_updates_open_reviews(self):
+        record = self.test_model.create({"test_field": 2.0})
+        review = record.with_user(self.test_user_2).request_validation()
+        self.definition.reviewer_user_ids = [(4, self.test_user_1.id)]
+        self.assertIn(self.test_user_1, review.reviewer_ids)
+
+    def test_four_eyes_principle(self):
+        self.definition.exclude_requester = True
+        record = self.test_model.create({"test_field": 2.0})
+        review = record.with_user(self.reviewer_a).request_validation()
+        self.assertEqual(review.reviewer_ids, self.reviewer_b)
+
+    def test_form(self):
+        with Form(self.tier_def_obj) as form:
+            form.model_id = self.tester_model
+            form.review_type = "users"
+            form.reviewer_user_ids.add(self.reviewer_a)
+        self.assertEqual(form.record.reviewer_user_ids, self.reviewer_a)
+        self.assertEqual(form.record._reviewers_to_check_for_access(), self.reviewer_a)
+        with Form(form.record) as form:
+            form.review_type = "individual"
+            form.reviewer_id = self.test_user_1
+        self.assertFalse(form.record.reviewer_user_ids)
diff --git a/base_tier_validation/views/tier_definition_view.xml b/base_tier_validation/views/tier_definition_view.xml
index ee9513715..75c2919f3 100644
--- a/base_tier_validation/views/tier_definition_view.xml
+++ b/base_tier_validation/views/tier_definition_view.xml
@@ -13,6 +13,11 @@
                 <field name="review_type" />
                 <field name="reviewer_id" />
                 <field name="reviewer_group_id" />
+                <field
+                    name="reviewer_user_ids"
+                    widget="many2many_avatar_user"
+                    optional="show"
+                />
                 <field name="reviewer_field_id" />
                 <field name="notify_on_create" optional="show" />
                 <field name="notify_on_pending" optional="show" />
@@ -63,6 +68,13 @@
                                 name="reviewer_group_id"
                                 invisible="review_type != 'group'"
                             />
+                            <field
+                                name="reviewer_user_ids"
+                                widget="many2many_avatar_user"
+                                invisible="review_type != 'users'"
+                                required="review_type == 'users'"
+                                options="{'no_create': True}"
+                            />
                             <field
                                 name="reviewer_field_id"
                                 invisible="review_type != 'field'"
@@ -93,7 +105,7 @@
                             </div>
                             <field
                                 name="exclude_requester"
-                                invisible="review_type != 'group'"
+                                invisible="review_type not in ('group', 'users')"
                             />
                         </group>
                     </group>
diff --git a/base_tier_validation_forward/tests/__init__.py b/base_tier_validation_forward/tests/__init__.py
index b439a531d..0dcdb5469 100644
--- a/base_tier_validation_forward/tests/__init__.py
+++ b/base_tier_validation_forward/tests/__init__.py
@@ -1,3 +1,4 @@
 # Copyright 2020 Ecosoft Co., Ltd. (http://ecosoft.co.th)
 # License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
 from . import test_tier_validation
+from . import test_forward_any_of_users
diff --git a/base_tier_validation_forward/tests/test_forward_any_of_users.py b/base_tier_validation_forward/tests/test_forward_any_of_users.py
new file mode 100644
index 000000000..937116087
--- /dev/null
+++ b/base_tier_validation_forward/tests/test_forward_any_of_users.py
@@ -0,0 +1,37 @@
+# License AGPL-3.0 or later (https://www.gnu.org/licenses/agpl).
+from odoo.tests import Form, new_test_user, tagged
+
+from odoo.addons.base_tier_validation.tests.common import CommonTierValidation
+
+
+@tagged("post_install", "-at_install")
+class TestForwardAnyOfUsers(CommonTierValidation):
+    def _setup_tier_definitions(self):
+        self.colleague = new_test_user(self.env, login="colleague", name="Clara")
+        self.tier_def_obj.create(
+            {
+                "model_id": self.tester_model.id,
+                "review_type": "users",
+                "reviewer_user_ids": [(6, 0, (self.test_user_2 | self.colleague).ids)],
+                "definition_domain": "[('test_field', '>', 1.0)]",
+                "has_forward": True,
+            }
+        )
+
+    def test_forward_keeps_only_the_new_reviewer(self):
+        """A forwarded review is for that user alone, not for the whole list."""
+        record = self.test_model.create({"test_field": 2.0})
+        record.with_user(self.test_user_1).request_validation()
+        record = record.with_user(self.test_user_2)
+        res = record.forward_tier()
+        wizard = Form(
+            self.env["tier.validation.forward.wizard"]
+            .with_user(self.test_user_2)
+            .with_context(**res["context"])
+        )
+        wizard.forward_reviewer_id = self.test_user_1
+        wizard.forward_description = "Please have a look"
+        wizard.save().add_forward()
+        record.invalidate_recordset()
+        forwarded = record.review_ids.filtered(lambda r: not r.definition_id)
+        self.assertEqual(forwarded.reviewer_ids, self.test_user_1)