Because of severe budget limitations, very few alien spacecraft actually appeared over the three seasons of the original "Star Trek." One of the first exceptions to this rule was the Romulan Bird-of-Prey, the centerpiece of the Season One episode "Balance of Terror." Shaped like a boot heel equipped with Federation-style warp nacelles, the Bird-of-Prey -- so named because of the hawk-like design painted on the craft's underbelly -- boasted a cloaking device and a powerful plasma weapon. The ship would appear in several subsequent episodes as well -- thanks to the magic of "stock shots."
