Rebel Minis have released a pack of 15mm Aliens for the 5150 sci-fi rules.
From their website:
Rebel Minis is proud to present our 15mm 5150 Aliens. Straight out of the best selling sci-fi rule system from Two Hour Wargames, these Aliens mean business. Each pack contains 5 Models. You get a Grath, a Razor and 3 different Hishen. Enter the 5150 universe and see what everyone is talking about.
Sculpted in amazing detail by Bobby Jackson.