The story of why Abraham Lincoln had a beard is one of the most famous anecdotes about him. Unlike many such stories, it actually is true. When he was running for president, an 11 year-old girl from upstate New York wrote to him urging him to grow his beard. She said she would try to persuade her brothers to vote for him if he did. She also told him that women would push their husbands to vote for him if he grew a beard because it would improve his excessively thin face. Read more here.
For me, another fun fact about Lincoln is that both of his parents were illiterate. It's hard to imagine that sort of thing today--a president coming from a family that uneducated. I also find it interesting that Lincoln was something of a tough guy in his youth. He was known for participating in wrestling matches which were a little more rough-and-tumble than things like high school wrestling today.