This is my favorite movie of all time. Many people may not agree with the regard in which I hold this movie but it's their loss in my opinion. Danny Boyle crafted a brilliant movie with awesome characters and brought fresh air to the "zombie" genre even though the "infected" are not zombies. Cillian Murphy also arrived on scene in this movie and he has been consistently excellent in just about every movie he has ever been in. The creativity that went into this story and production was just fantastic and the movie has the perfect blend of realism, brutality, and fantasy. This is a movie that you can see eventually playing out in real life and I think that is what made it so frightening in people's minds when they first saw the movie.
The Walking Dead has also borrowed very liberally from this movie and most people really don't realize it. The fact that the main character that landed him in a coma before everything started and then waking up in an abandoned hospital. Also being in a deserted city and then being taken in by a small group that caught him up to speed. The character of Michonne in the Walking Dead is a loose copy of the character of Selena in 28 Days Later. This movie really has had a large effect on the horror community in general spreading through not just movies but also comics and video games. The funny thing is that 28 Days Later isn't a zombie movie because the people in the movie are infected with a Rage virus so technically they could have been cured. Cillian Murphy also became one of personal favorite actors as a result of seeing this movie. His work in this movie and in the movie Sunshine (another top 10 movie) is just superb. He does a great job playing the everyman in the movie and being the eyes and ears for the viewers because they both have the same amount of info as the movie progresses. The movie was also anchored by a variety of believable and solid characters. Boyle has an uncanny ability to get the audience to care for the characters he creates and he even had to change the original ending because test audiences didn't think that a certain character should die in the movie (and I agree with their opinion). This is just a very special movie in my opinion and it is going to take a truly special movie to dethrone this movie in my eyes.
This happens to be one of the most influential movies to be personally because I really judge all horror movies off of this one. The only other horror movie that even comes close to this one is Shaun of the Dead and they could easily flip flop on my list of all time favorites due to my mood on a given day. This is one of those movie that I would recommend everyone see even though I know not everyone will like the movie.