Using the SolidColorBrush and Color type
<Window xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation" xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml" Title="SolidColorBrush Animation Example" Background="White"> <StackPanel> <Ellipse Height ="50" Width ="50"> <Ellipse.Fill> <SolidColorBrush> <SolidColorBrush.Color> <Color A ="40" R ="100" G ="87" B ="98"/> </SolidColorBrush.Color> </SolidColorBrush> </Ellipse.Fill> </Ellipse> </StackPanel> </Window>