I loved watching Sagan's cosmos when I was young. So, I will say Carl Sagan!

I disagree that you older people have more to choose from... There are many more people now who have changed my mind from a simple comment on a thread. So many people have influenced my life I couldn't possibly know who is the most important. You older people only had your best and brightest authors available to everyone, I'm almost 40 now and I've met so many people online and in real life that even the complete idiots have changed how I look at things because I learned how they view things which is a completely different way than I do.

Everyone I've talked to or read have been equally important, every little bit I've learned has molded me into who I am.

I have to go with Carl Sagan. I found out about him at a young age and have most of his books. He did his best to educate the world, sadly only some of us were open to learning.

I am saying Martin Luther King Jr. He pushed for equal rights and protesting peacefully.

My younger self, damned I would sell everything to be that naive again.

Nelson Mandela

My vote goes to the Dalai Lama, he has done some wonderful work promoting kindness and the interaction of science and Buddhism.

JFK. For all his indiscretions, he gave hope to my generation.

Ghandi.

Mom... President Barack Obama... history will define his greatness... if we survive.
Mr Nelson Mandella... Mr Robert Kennedy.

Eleanore Roosevelt

Noam Chomsky.
he is just so authentic and wise, but mainly speaks so well.

Christopher Hitchens had the biggest impact on me.

Richard Feynman.

Rachel Carson.

Well tough choice on my final 2...
His Holiness The Dalai Lama

My 2nd choice...
Mr President Jimmy Carter...
Greatest president of my lifetime.

My father.

George Franklin- high school math teacher.

It really is a difficult one. Even the 'greats' were flawed in some way and quite often have a situation thrust upon them to which they responded magnificently, Churchill being the person who came to mind while writing this.
The other problem, for me at least, is not knowing enough, or indeed anything, about a person so my impression is based on very little but in recent years Christopher Hitchins, when I finally came across him, seem to articulate exactly what i was thinking about religion but in a far better way, and then from being exposed to him came Harris, Dawkins, Dennett et al. I would also include Thomas Payne here as well although it's his legacy that is in my lifetime.
Closer to home people like my brother, an outward persona of grumpy old sod, but a man who has dealt with personal tragedy and difficulties with a fortitude, common sense and humour that is admirable.
I would also give someone like Wenn Lawson a mention, you may need to look him up, an autistic guy who's life story is remarkable and he travels the world educating people on the condition. And he's a really nice bloke as well.

Btw, nice question with some terrific (and slightly odd) answers

I think comedy holds the greatest truths about humanity because it is rooted in the tragedy that we all live through at some points in our lives but it spins it and makes it a learning experience and an uplifting experience, so my vote is for George Carlin.

RobLawrence. i’m glad you liked my reply, I once was asked who I would most like to spend an evening with if i could choose any living person......it only took me a few minutes to say David Attenborough. He is also a Humanist like myself and although he’s ninety woiuld beat most others hands down. The other one, well he is the lead singer of A-ha the Norwegian band. Don‘t think me shallow when I say it, but if it were on looks alone Morten Harket would have to be first choice, but he is the complete package, looks, humanitarianism and the best voice in popular music!

If I had to pick one it would be Stephen Hawking. I would have chosen him for his amazing intelligence and imagination anyway, but the difficulties he overcame while displaying those attributes makes him a true hero of mine.

I have two. Sir David Attenborough and Morten Harket. The first because is such an incredible human being and cares so much for our planet. The second for his humanitarian work and his incredible 4+octave voice, and his unbelievable handsomeness!

Ansel Adams

I really liked Tony Wedgewood Benn U.K. politician he was kindly and a gentleman and loved to engage with people he was funny too because he thought he was sort of a man who could carry off being working class by taking his own beer mug to the pub