[PersistenceMode(PersistenceMode.InnerProperty)]
[XtraChartsLocalizableCategory(XtraChartsCategory.Elements)]
public CustomLegendItemCollection CustomItems { get; }

<XtraChartsLocalizableCategory(XtraChartsCategory.Elements)>
<PersistenceMode(PersistenceMode.InnerProperty)>
Public ReadOnly Property CustomItems As CustomLegendItemCollection

using DevExpress.Drawing;
using DevExpress.XtraCharts;
using System;
using System.IO;
using System.Windows.Forms;

namespace CustomLegendItemSample {
    public partial class Form1 : Form {
        public Form1() {
            InitializeComponent();
        }
        private void Form1_Load(object sender, EventArgs e) {
            #region #CustomLegendItems
            // Create a new custom item.
            CustomLegendItem item = new CustomLegendItem();
            chart.Legend.CustomItems.Add(item);
            // Specify its text and marker.
            item.Text = "Custom Legend Item";
            FileStream outfile = new FileStream("Image\\DXLogo_16x16.png", FileMode.Open);
            DXImage image = DXImage.FromStream(outfile);
            item.MarkerImage.DXImage = image;

            // Set a value indicating that both autogenerated and custom items are displayed.
            chart.Legend.ItemVisibilityMode = LegendItemVisibilityMode.AutoGeneratedAndCustom;
            #endregion #CustomLegendItems
        }
    }
}

Imports DevExpress.Drawing
Imports DevExpress.XtraCharts
Imports System
Imports System.IO
Imports System.Windows.Forms

Namespace CustomLegendItemSample

    Public Partial Class Form1
        Inherits Form

        Public Sub New()
            InitializeComponent()
        End Sub

        Private Sub Form1_Load(ByVal sender As Object, ByVal e As EventArgs)
#Region "#CustomLegendItems"
            ' Create a new custom item.
            Dim item As CustomLegendItem = New CustomLegendItem()
            chart.Legend.CustomItems.Add(item)
            ' Specify its text and marker.
            item.Text = "Custom Legend Item"
            Dim outfile As FileStream = New FileStream("Image\DXLogo_16x16.png", FileMode.Open)
            Dim image As DXImage = DXImage.FromStream(outfile)
            item.MarkerImage.DXImage = image
            ' Set a value indicating that both autogenerated and custom items are displayed.
            chart.Legend.ItemVisibilityMode = LegendItemVisibilityMode.AutoGeneratedAndCustom
#End Region ' #CustomLegendItems
        End Sub
    End Class
End Namespace