1-Michael Hart said in his book The 100: A Ranking of the Most Influential Persons in History (p. 13), where he put Muhammad (sallallahu alaihi wa’sallam) at the head of his list of one hundred:
I chose Muhammad (sallallahu alaihi wa’sallam) to be top of this list … because Muhammad (sallallahu alaihi wa’sallam) was the only man in history who was supremely successful on both the religious and secular levels.

2-The Englishman George Bernard Shaw wrote a book called Muhammad, which was burned by the British authorities. He said:
The world is in the utmost need of a man with the mentality of Muhammad.
Medieval ecclesiastics, either through ignorance of bigotry, painted Mohammadanism in the darkest colors. They were in fact; trained to hate both the man Muhammad (sallallahu alaihi wa’sallam) and his to them was anti-Christ. But I have studied his life, and found him to be extraordinary. I have reached the conclusion that he was never an enemy to Christianity. He must be called the Saviour of Humanity. I believe that if a man like him were to assume the dictatorship of the modern world, he would succeed in solving its problems in a way that would bring it much needed peace and happiness.

3-Annie Besant said:
It is impossible for anyone who studies the life and character of the great Prophet of Arabia, who knows how he taught and how he lived, to feel anything but reverence for that mighty Prophet, one of the great messengers of the Supreme.

4-The Austrian Schabrak said:
Mankind may be proud of having a man like Muhammad (sallallahu alaihi wa’sallam) among them, for despite being illiterate he was able more than ten centuries ago to introduce legislation that we Europeans would be the happiest ever if we could produce something of equally high quality.

5-Dr. Zwemer (a Canadian Orientalist):
Muhammad (sallallahu alaihi wa’sallam) was an able reformer, eloquent and well spoken, courageous and daring, a great thinker. We cannot attribute to him anything that contradicts these qualities. This Qur’aan that he brought and his history bear witness to the truth of these claims.

6-The English philosopher Thomas Carlyle, the Nobel Prize winner, says in his book Heroes:
It is very shameful for any individual in this era to listen to what is said about the religion of Islam being a fabrication and Muhammad (sallallahu alaihi wa’sallam) being a treacherous fabricator. Throughout his life we see him holding firm beliefs, sincere in resolve, generous and kind, compassionate, pious, virtuous, very serious. In spite of that, he was easy-going, cheerful, friendly, and even sometimes light-hearted. He was just, sincere in intention, smart, chivalrous, and quick-witted, as if he carried in his heart the lamps of every dark night, filled with light; a naturally great man who never studied in school or at the hand of a teacher, because he had no need of that.

7-Goethe, the German poet, said:
We Europeans with all our concepts and ideas have not yet attained that which Muhammad (sallallahu alaihi wa’sallam) attained, and no one will ever surpass him. I searched in history for the loftiest example for man to follow, and I found it in the Prophet Muhammad. Thus the truth must prevail and become supreme, because Muhammad (sallallahu alaihi wa’sallam) succeeded in subjugating the whole world by means of the message of Divine Oneness.

8-Mahatma Gandhi
Speaking on the character of Muhammad (sallallahu alaihi wa’sallam), Mahatma Gandhi says in (Young India),
"I wanted to know the best of one who holds today's undisputed sway over the hearts of millions of mankind....I became more than convinced that it was not the sword that won a place for Islam in those days in the scheme of life. It was the rigid simplicity, the utter self-effacement of the Prophet, the scrupulous regard for his pledges, his intense devotion to this friends and followers, his intrepidity, his fearlessness, his absolute trust in God and in his own mission. These and not the sword carried everything before them and surmounted every obstacle. When I closed the 2nd volume (of the Prophet's biography), I was sorry there was not more for me to read of the great life."