diff --git a/rclpy/rclpy/executors.py b/rclpy/rclpy/executors.py
index 0aa6d1824..e61986e50 100644
--- a/rclpy/rclpy/executors.py
+++ b/rclpy/rclpy/executors.py
@@ -34,6 +34,8 @@
 
 
 from rclpy.client import Client
+from rclpy.clock import Clock
+from rclpy.clock import ClockType
 from rclpy.context import Context
 from rclpy.guard_condition import GuardCondition
 from rclpy.handle import InvalidHandle
@@ -43,7 +45,7 @@
 from rclpy.subscription import Subscription
 from rclpy.task import Future
 from rclpy.task import Task
-from rclpy.timer import WallTimer
+from rclpy.timer import Timer
 from rclpy.utilities import get_default_context
 from rclpy.utilities import timeout_sec_to_nsec
 from rclpy.waitable import NumberOfEntities
@@ -168,6 +170,8 @@ def __init__(self, *, context: Context = None) -> None:
         self._cb_iter = None
         self._last_args = None
         self._last_kwargs = None
+        # Executor cannot use ROS clock because that requires a node
+        self._clock = Clock(clock_type=ClockType.STEADY_TIME)
         self._sigint_gc = SignalHandlerGuardCondition(context)
         self._context.on_shutdown(self.wake)
 
@@ -437,7 +441,7 @@ def _wait_for_ready_callbacks(
         timeout_timer = None
         timeout_nsec = timeout_sec_to_nsec(timeout_sec)
         if timeout_nsec > 0:
-            timeout_timer = WallTimer(None, None, timeout_nsec)
+            timeout_timer = Timer(None, None, timeout_nsec, self._clock)
 
         yielded_work = False
         while not yielded_work and not self._is_shutdown:
@@ -463,7 +467,7 @@ def _wait_for_ready_callbacks(
             # Gather entities that can be waited on
             subscriptions: List[Subscription] = []
             guards: List[GuardCondition] = []
-            timers: List[WallTimer] = []
+            timers: List[Timer] = []
             clients: List[Client] = []
             services: List[Service] = []
             waitables: List[Waitable] = []
diff --git a/rclpy/rclpy/node.py b/rclpy/rclpy/node.py
index fa6f5601e..c95115e0c 100644
--- a/rclpy/rclpy/node.py
+++ b/rclpy/rclpy/node.py
@@ -65,7 +65,7 @@
 from rclpy.service import Service
 from rclpy.subscription import Subscription
 from rclpy.time_source import TimeSource
-from rclpy.timer import WallTimer
+from rclpy.timer import Timer
 from rclpy.type_support import check_for_type_support
 from rclpy.utilities import get_default_context
 from rclpy.validate_full_topic_name import validate_full_topic_name
@@ -137,7 +137,7 @@ def __init__(
         self.__subscriptions: List[Subscription] = []
         self.__clients: List[Client] = []
         self.__services: List[Service] = []
-        self.__timers: List[WallTimer] = []
+        self.__timers: List[Timer] = []
         self.__guards: List[GuardCondition] = []
         self.__waitables: List[Waitable] = []
         self._default_callback_group = MutuallyExclusiveCallbackGroup()
@@ -214,7 +214,7 @@ def services(self) -> Iterator[Service]:
         yield from self.__services
 
     @property
-    def timers(self) -> Iterator[WallTimer]:
+    def timers(self) -> Iterator[Timer]:
         """Get timers that have been created on this node."""
         yield from self.__timers
 
@@ -1281,8 +1281,9 @@ def create_timer(
         self,
         timer_period_sec: float,
         callback: Callable,
-        callback_group: CallbackGroup = None
-    ) -> WallTimer:
+        callback_group: CallbackGroup = None,
+        clock: Clock = None,
+    ) -> Timer:
         """
         Create a new timer.
 
@@ -1293,11 +1294,14 @@ def create_timer(
         :param callback: A user-defined callback function that is called when the timer expires.
         :param callback_group: The callback group for the timer. If ``None``, then the nodes
             default callback group is used.
+        :param clock: The clock which the timer gets time from.
         """
         timer_period_nsec = int(float(timer_period_sec) * S_TO_NS)
         if callback_group is None:
             callback_group = self.default_callback_group
-        timer = WallTimer(callback, callback_group, timer_period_nsec, context=self.context)
+        if clock is None:
+            clock = self._clock
+        timer = Timer(callback, callback_group, timer_period_nsec, clock, context=self.context)
         timer.handle.requires(self.handle)
 
         self.__timers.append(timer)
@@ -1385,7 +1389,7 @@ def destroy_service(self, service: Service) -> bool:
             return True
         return False
 
-    def destroy_timer(self, timer: WallTimer) -> bool:
+    def destroy_timer(self, timer: Timer) -> bool:
         """
         Destroy a timer created by the node.
 
diff --git a/rclpy/rclpy/timer.py b/rclpy/rclpy/timer.py
index c96ea3798..f69f66a5c 100644
--- a/rclpy/rclpy/timer.py
+++ b/rclpy/rclpy/timer.py
@@ -12,20 +12,16 @@
 # See the License for the specific language governing permissions and
 # limitations under the License.
 
-from rclpy.clock import Clock
-from rclpy.clock import ClockType
 from rclpy.handle import Handle
 from rclpy.impl.implementation_singleton import rclpy_implementation as _rclpy
 from rclpy.utilities import get_default_context
 
 
-# TODO(mikaelarguedas) create a Timer or ROSTimer once we can specify custom time sources
-class WallTimer:
+class Timer:
 
-    def __init__(self, callback, callback_group, timer_period_ns, *, context=None):
+    def __init__(self, callback, callback_group, timer_period_ns, clock, *, context=None):
         self._context = get_default_context() if context is None else context
-        # TODO(sloretz) Allow passing clocks in via timer constructor
-        self._clock = Clock(clock_type=ClockType.STEADY_TIME)
+        self._clock = clock
         with self._clock.handle as clock_capsule:
             self.__handle = Handle(_rclpy.rclpy_create_timer(
                 clock_capsule, self._context.handle, timer_period_ns))