diff --git a/NEWS.md b/NEWS.md
index 0fd950dcf6..6e0540dd85 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -6,8 +6,8 @@
   (@mitchelloharawild, #6609).
 * Fixed regression where `scale_{x,y}_*()` threw an error when an expression
   object is set to `labels` argument (@yutannihilation, #6617).
-
-
+* `stat_ydensity()` now only requires the `x` or `y` aesthetic. The other will
+  be populated with 0, similar to `stat_boxplot()` (@teunbrand, #6600)
 * Allow `stat` in `geom_hline`, `geom_vline`, and `geom_abline`. (@sierrajohnson, #6559)
 
 # ggplot2 4.0.0
diff --git a/R/stat-ydensity.R b/R/stat-ydensity.R
index 969723ebd4..01a862cdc1 100644
--- a/R/stat-ydensity.R
+++ b/R/stat-ydensity.R
@@ -4,7 +4,7 @@
 #' @export
 StatYdensity <- ggproto(
   "StatYdensity", Stat,
-  required_aes = c("x", "y"),
+  required_aes = "x|y",
   non_missing_aes = "weight",
 
   setup_params = function(data, params) {
@@ -23,6 +23,12 @@ StatYdensity <- ggproto(
     params
   },
 
+  setup_data = function(self, data, params) {
+    var <- flipped_names(flip = params$flipped_aes)$x
+    data[[var]] <- data[[var]] %||% 0
+    data
+  },
+
   # `draw_quantiles` is here for deprecation repair reasons
   extra_params = c("na.rm", "orientation", "draw_quantiles"),