There is nobody I have tried to live without in order to establish I can not live without them. That eliminates people from this answer.
I have tried living without Downy dryer sheets. It was not fun. I went to great lengths to obtain them. I pretty much haven't tried to live without anything I think is vital to my living, so this is another question which just isn't easy for me to answer.
I could not live my life without corrective lenses. I could still be alive, but not really live the life I do now. But again, I haven't tried to go without them. Not unless you count the five minutes I was without them yesterday while Gretchen was fixing hem for me.