1. Dwayne Johnson
It's such a shame that one of my favourite action stars has made it to the number one spot, but I have to go with my instincts on this one. We all know how fake and predictable Wrestlers can be when they try to tough talk their opponents or try to look cool. We kinda like it at the time but apply the same behaviour to real-life and you're likely to be laughed out of existence. To be fair to Dwayne, his brief appearance in the Voyager season 6 episode "Tsunkatse" came at what was essentially his transnational period between Wrestling and proper acting, so he has my forgiveness, but he still has to be immortalised as the worst guest star of the Star Trek franchise. The character he portrayed was a champion fighter in the Tsunkatse arena who has a showdown with Seven of Nine. What made his performance so cringe-worthy was the fact that he played it basically as 'The Rock', even inflicting his signature 'Rock Bottom' move on Seven. Sure, many of us loved 'The Rock' as a wrestling character, but if you're going to move from wrestling to acting in TV shows, you've got to be just a little bit flexible. Slapping some forehead ridges on your face doesn't qualify. Perhaps he should have chosen a less 'Rock' style role while making this transition. Thankfully he has moved on and become a household name as 'Dwayne Johnson' rather than 'The Rock'.