For a gain of 0.5, all you need is a resistor divider. If your load impedance is low, you will need a unity gain non-inverting amplifier (voltage follower) after the divider to drive the load. If the source is high impedance, you might need to put the follower first, and then the divider. In the case where source and load are both high impedance, you could require two voltage followers, with a divider between them.
What are you trying to drive, and what is the signal source?