9. Jeri Ryan And Kate Mulgrew
It is little secret these days that Jeri Ryan's introduction to Star Trek was not the smoothest entry for a new cast member. She was written into the show at the cost of Jennifer Lien, although Lien's fate had been decided in advance. The character of Seven of Nine was introduced to boost ratings, which certainly did work, but it came with another issue.
Star Trek: Voyager has rightly been lauded for being one of the biggest steps that the franchise took in showcasing gender equality. This was the first series to be led by a woman, with Kate Mulgrew playing Captain Janeway. The writers and producers struggled a little in the early series to strike the right tone with the character but, by the end of the third season, things had settled into place.
Janeway was not a sex symbol, and by this we mean that she was not characterised in revealing costume, nor did she ever fall to 'damsel in distress depiction.' She was an excellent female role model, with Mulgrew delighted at this. The introduction of Seven of Nine, who most certainly was created as a sex symbol, upset Mulgrew as she felt it could undo some of the great strides that the show had made.
Unfortunately, Mulgrew directed her ire toward Jeri Ryan. Tensions were very high on set and, despite the two actors sharing many scenes together, they barely spoke for the duration of their time together.
However, this has a slightly happier ending. In recent years, Mulgrew has owned and apologised for what she recognised as unfair behaviour toward Ryan. Based on recent convention appearances, it seems that the two have buried the hatchet.