9. Star Trek Voyager - In The Flesh
Species 8472 were the largest scale, entirely digital race that were created for Star Trek Voyager and so singling them out may come across as slightly harsh. However, this particular scene lands on this list because it is a disappointing entry to Species 8472's canon.
The big reveal in sickbay during the episode was designed to be a shocking moment. The Doctor administers his treatment that will reverse the DNA sequencing and both he and Janeway show shock and fear. However, the thing they fear is neither shocking nor frightening.
For their first appearance in the show, 8472 was shrouded mostly in darkness and when the ships began to attack, it was an entirely CGI scene. This scene however shows the digital creature superimposed on the sickbay set, with two defined actors only serving to highlight the soft, CGI edge in the foreground. With the limitations of television budgeting available, it is entirely forgivable to attempt this as, the alternative (guy in a suit) would have looked equally ridiculous.
It is somewhat fair to say though that the members of 8472 who are played by human actors in this episode serve a far better purpose for the plot than the CGI puppet in sickbay and the more time that is spent with them raises the overall quality of the episode.