WPF circle button example

    <Grid>
        <Button  Width="50" Height="50" Content="Click me!" Click="Button_Click">
            <Button.Template>
                <ControlTemplate TargetType="Button">
                    <Grid>
                        <Ellipse Fill="Violet"/>
                        <ContentPresenter HorizontalAlignment="Center" VerticalAlignment="Center"/>
                    </Grid>
                </ControlTemplate>
            </Button.Template>
        </Button>
    </Grid>

private void Button_Click(object sender, RoutedEventArgs e)
{
    MessageBox.Show("I am circle button");
}