Albert Einstein was a brilliant scientist who changed the way people viewed the universe.
You will probably recognise this picture.
Einstein was so famous that lots of actors, playing professors, have copied his looks. But people who knew him say he was nothing like the mad scientist stereotype.
His face as an old man has become well-known but he actually did his best work at the age of 26.
Einstein was born in Ulm, Germany in 1879 and grew up in Munich.
He dropped out of school and was rejected from several universities.
Eventually, he got into the Swiss Polytechnic in Zurich where he studied to be a teacher.
He married one of his classmates, Mileva Maric, and the couple had three children.
But they later divorced and Einstein married his cousin Elsa L÷wenthal.
After failing to find a teaching job, he found work in an office checking out other people's inventions.
But in his spare time he was putting together some brilliant scientific ideas.
When people realised how clever he was, he became a professor four times and was given an honorary degrees from many universities including Oxford and Cambridge, Manchester and London.
He won the Nobel Prize for Physics in 1921 for showing that light was not just made up of waves, it could also be thought of as individual packets of light or photons.
He died in 1955 at the age of 76.
Einstein once said that his greatest gifts were stubbornness and taking seriously the sorts of questions only children ask.