T Toys [Tai Hing] made a range of cool plastic flying saucer toys. The two basic types are the UFO, of which there is only one version, red and yellow as pictured below, and the more prolific Moon Ranger Mercury Mark IV seen above with pal Robby. All of them have a cloudy astrodome, four corner domes and an aeriel.
The Moon Ranger Mercury Mark IV was made both by T Toys and Clifford. It has corner domes with pilots and a metal aerial. There are a number of colour schemes, which I'm aware of, as you can see here. Pictures of any further versions welcomed.
Above are yellow - silver and red - blue versions with the same box by both T and Clifford respectively I think. the right hand red version has what appears to be a plastic aerial as does the yellow and red variant below.
Above we have a lime green and silver variant with its T box.
Finally we have two different shades of blue. The above all-blue version has a different name: "Space Ship Mercury Mark IV" and is unbranded. The light blue and version below is a hybrid of both the UFO and Moon Ranger as it has striped tape around its centre and a plastic aerial
Picture credits: Woodsy, Ebay, Alphadrome and Vectis.