diff --git a/NEWS.md b/NEWS.md
index c0f7809db6..d8167c66c9 100644
--- a/NEWS.md
+++ b/NEWS.md
@@ -1,5 +1,7 @@
 # ggplot2 (development version)
 
+* The `fatten` argument has been deprecated in `geom_boxplot()`, 
+  `geom_crossbar()` and `geom_pointrange()` (@teunbrand, #4881).
 * Axis labels are now preserved better when using `coord_sf(expand = TRUE)` and
   graticule lines are straight but do not meet the edge (@teunbrand, #2985).
 * Attempt to boost detail in `coord_polar()` and `coord_radial()` near the 
diff --git a/R/geom-boxplot.R b/R/geom-boxplot.R
index edd6117538..96c6ed9d35 100644
--- a/R/geom-boxplot.R
+++ b/R/geom-boxplot.R
@@ -239,6 +239,15 @@ GeomBoxplot <- ggproto("GeomBoxplot", Geom,
   extra_params = c("na.rm", "orientation", "outliers"),
 
   setup_params = function(data, params) {
+    if ("fatten" %in% names(params)) {
+      deprecate_soft0(
+        "3.6.0", "geom_boxplot(fatten)",
+        "geom_boxplot(median.linewidth)"
+      )
+    } else {
+      # For backward compatibility reasons
+      params$fatten <- 2
+    }
     params$flipped_aes <- has_flipped_aes(data, params)
     params
   },
diff --git a/R/geom-crossbar.R b/R/geom-crossbar.R
index 7316033de6..8f9d8ccd74 100644
--- a/R/geom-crossbar.R
+++ b/R/geom-crossbar.R
@@ -17,7 +17,7 @@ geom_crossbar <- function(mapping = NULL, data = NULL,
                           box.color         = NULL,
                           box.linetype      = NULL,
                           box.linewidth     = NULL,
-                          fatten = 2.5,
+                          fatten = deprecated(),
                           na.rm = FALSE,
                           orientation = NA,
                           show.legend = NA,
@@ -60,6 +60,15 @@ geom_crossbar <- function(mapping = NULL, data = NULL,
 #' @export
 GeomCrossbar <- ggproto("GeomCrossbar", Geom,
   setup_params = function(data, params) {
+    if (lifecycle::is_present(params$fatten)) {
+      deprecate_soft0(
+        "3.6.0", "geom_crossbar(fatten)",
+        "geom_crossbar(middle.linewidth)"
+      )
+    } else {
+      # For backward compatibility reasons
+      params$fatten <- 2.5
+    }
     GeomErrorbar$setup_params(data, params)
   },
 
diff --git a/R/geom-linerange.R b/R/geom-linerange.R
index 085d8f98a9..71c0799971 100644
--- a/R/geom-linerange.R
+++ b/R/geom-linerange.R
@@ -6,9 +6,9 @@
 #' @eval rd_orientation()
 #'
 #' @eval rd_aesthetics("geom", "linerange", "Note that `geom_pointrange()` also understands `size` for the size of the points.")
-#' @param fatten A multiplicative factor used to increase the size of the
-#'   middle bar in `geom_crossbar()` and the middle point in
-#'   `geom_pointrange()`.
+#' @param fatten `r lifecycle::badge("deprecated")`  A multiplicative factor
+#'   used to increase the size of the middle bar in `geom_crossbar()` and the
+#'   middle point in `geom_pointrange()`.
 #' @seealso
 #'  [stat_summary()] for examples of these guys in use,
 #'  [geom_smooth()] for continuous analogue
diff --git a/R/geom-pointrange.R b/R/geom-pointrange.R
index d0e5194311..1943bb4f4c 100644
--- a/R/geom-pointrange.R
+++ b/R/geom-pointrange.R
@@ -3,7 +3,7 @@
 geom_pointrange <- function(mapping = NULL, data = NULL,
                             stat = "identity", position = "identity",
                             ...,
-                            fatten = 4,
+                            fatten = deprecated(),
                             na.rm = FALSE,
                             orientation = NA,
                             show.legend = NA,
@@ -42,6 +42,12 @@ GeomPointrange <- ggproto("GeomPointrange", Geom,
   required_aes = c("x", "y", "ymin|xmin", "ymax|xmax"),
 
   setup_params = function(data, params) {
+    if (lifecycle::is_present(params$fatten)) {
+      deprecate_soft0("3.6.0", "geom_pointrange(fatten)", I("the `size` aesthetic"))
+    } else {
+      # For backward compatibility reasons
+      params$fatten <- 4
+    }
     GeomLinerange$setup_params(data, params)
   },
 
diff --git a/man/geom_linerange.Rd b/man/geom_linerange.Rd
index 93f340656e..0c77084236 100644
--- a/man/geom_linerange.Rd
+++ b/man/geom_linerange.Rd
@@ -23,7 +23,7 @@ geom_crossbar(
   box.color = NULL,
   box.linetype = NULL,
   box.linewidth = NULL,
-  fatten = 2.5,
+  fatten = deprecated(),
   na.rm = FALSE,
   orientation = NA,
   show.legend = NA,
@@ -72,7 +72,7 @@ geom_pointrange(
   stat = "identity",
   position = "identity",
   ...,
-  fatten = 4,
+  fatten = deprecated(),
   na.rm = FALSE,
   orientation = NA,
   show.legend = NA,
@@ -160,9 +160,9 @@ data's aesthetics.}
 \item{box.colour, box.color, box.linetype, box.linewidth}{Default aesthetics for the boxes. Set to \code{NULL} to inherit from the
 data's aesthetics.}
 
-\item{fatten}{A multiplicative factor used to increase the size of the
-middle bar in \code{geom_crossbar()} and the middle point in
-\code{geom_pointrange()}.}
+\item{fatten}{\ifelse{html}{\href{https://lifecycle.r-lib.org/articles/stages.html#deprecated}{\figure{lifecycle-deprecated.svg}{options: alt='[Deprecated]'}}}{\strong{[Deprecated]}}  A multiplicative factor
+used to increase the size of the middle bar in \code{geom_crossbar()} and the
+middle point in \code{geom_pointrange()}.}
 
 \item{na.rm}{If \code{FALSE}, the default, missing values are removed with
 a warning. If \code{TRUE}, missing values are silently removed.}