yohaidajurno · Jun 29, 2026 · Jun 30, 2026
diff --git a/doc/api/next_api_changes/behavior/empty_bar_legend.rst b/doc/api/next_api_changes/behavior/empty_bar_legend.rst
@@ -0,0 +1,7 @@
+Legend entry of an empty bar plot reflects the requested style
+--------------------------------------------------------------
+
+Calling `~matplotlib.axes.Axes.bar` with empty data previously produced a
+legend entry with the default style and the first color of the property cycle.
+The legend entry now reflects the requested bar style (e.g. *color*, *alpha*),
+consistent with `~matplotlib.axes.Axes.plot` and `~matplotlib.axes.Axes.scatter`.
diff --git a/lib/matplotlib/axes/_axes.py b/lib/matplotlib/axes/_axes.py
@@ -2646,6 +2646,23 @@ def bar(self, x, height, width=0.8, bottom=None, *, align="center",
         bar_container = BarContainer(patches, errorbar, datavalues=datavalues,
                                      orientation=orientation,
                                      label=bar_container_label)
+        if not patches:
+            # No bars were created (e.g. empty data), so there is no child
+            # artist to carry the requested style into the legend.  Stash a
+            # non-drawn sample Rectangle with the resolved style so the legend
+            # entry still reflects it, consistent with plot()/scatter().
+            # facecolor/edgecolor are not broadcast against the (empty) data,
+            # so they still carry the resolved style; linewidth/hatch were
+            # broadcast and may be exhausted, so fall back to the defaults.
+            sample = mpatches.Rectangle(
+                xy=(0, 0), width=0, height=0,
+                facecolor=next(facecolor),
+                edgecolor=next(edgecolor),
+                linewidth=next(linewidth, None),
+                hatch=next(hatch, None),
+                )
+            sample._internal_update(kwargs)
+            bar_container._sample_patch = sample
         self.add_container(bar_container)
 
         if tick_labels is not None:

diff --git a/lib/matplotlib/legend_handler.py b/lib/matplotlib/legend_handler.py
@@ -39,6 +39,10 @@ def legend_artist(self, legend, orig_handle, fontsize, handlebox)
 
 def update_from_first_child(tgt, src):
     first_child = next(iter(src.get_children()), None)
+    if first_child is None:
+        # Containers with no children (e.g. a bar plot of empty data) may carry
+        # a non-drawn sample artist describing the intended style.
+        first_child = getattr(src, '_sample_patch', None)
     if first_child is not None:
         tgt.update_from(first_child)
 

diff --git a/lib/matplotlib/tests/test_legend.py b/lib/matplotlib/tests/test_legend.py
@@ -663,6 +663,16 @@ def test_empty_bar_chart_with_legend():
     plt.legend()
 
 
+def test_empty_bar_chart_legend_handle_style():
+    # Issue #21506: a bar plot of empty data should still produce a legend
+    # entry styled like the requested bars (consistent with plot()/scatter()),
+    # rather than falling back to the default style and color.
+    fig, ax = plt.subplots()
+    ax.bar([], [], color='red', alpha=0.3, label='empty')
+    handle = ax.legend().legend_handles[0]
+    assert_allclose(handle.get_facecolor(), mpl.colors.to_rgba('red', 0.3))
+
+
 @image_comparison(['shadow_argument_types.png'], remove_text=True, style='mpl20',
                   tol=0 if platform.machine() == 'x86_64' else 0.028)
 def test_shadow_argument_types():