Unicorns were really single-horned rhinos.
"Unicorns" were actually single-horned rhinos (the Indian Rhinoceros), which were used as beasts of war in ancient times. They were misinterpreted as a mythical creature.
The historical figure Genghis Khan documented that he called off the invasion of India due to witnessing 'terrible and brutal one-horned beasts ridden by man', which today we understand were War Rhinos, similar to War Elephants. They were also mentioned by an Ancient Greek called Ctesias.
The documents were misinterpreted, hence the myth of unicorns was born. When in reality, they were actually Indian Rhinos.
So to answer your question, yes, the Indian Rhino (aka "unicorn") has been seen.
See this related question: Do Unicorns Exist?
Imagination Movers - 2008 Have You Ever Seen a Unicorn was released on: USA: 7 May 2012
NO`I hope dragons are real besides the Komodo dragon.
No-one has ever produced proof of the unicorns' existence. Therefore, there is no definitive answer to this question.
no
I believe there is no one who has ever seen an angel
No. They are not real.
The weirdest thing happened to me yesterday when I saw a unicorn in my backyard.
Not that anyone knows and has proven.
No nobody has ever seen an atom or atoms, though many people/scientists claim they have, NOBODY HAS EVER SEEN AN ATOM!
yes it is true
many people actually (in their dreams)
No. They are not real so they do not exist. Therefore no one has seen them.