Sir Walter Raleigh was born into the nobility into a Protestant family. During the reign of Mary I, being a Protestant was extremely dangerous, and at one point, Raleigh's father had to hide in a tower to avoid being executed.
When Elizabeth I came to the throne, things improved for the Raleigh family. Walter Raleigh was a poet and a nobleman, and very popular with the queen.
In 1584, she granted him a royal charter to explore and rule any territory in the world that didn't have a Christian prince. She must have been hoping he would colonise parts of the Americas that the Spanish hadn't reached. But instead, he got someone else to found a colony for him on Roanoke Island. It didn't turn out well, because the settlers disappeared when the colony's governor had to nip home to England for more supplies, and didn't get back until three years later.
Sir Walter Raleigh, painted by Nicholas Hilliard. Frills were obviously all the rage, as were pointy little beards!
In the meantime, Raleigh took tobacco with him back to England, and helpfully popularised the smoking of it. According to one story, his maid had to throw a bucket of water over him after he set fire to himself with his pipe. But people still didn't realise for several hundred years how dangerous it truly was. In 1585, Queen Elizabeth knighted Raleigh, though probably not for his services to the tobacco industry or for pioneering an excellent way of getting lung cancer.
Sir Walter Raleigh's time in favour with the queen didn't last. When he secretly married one of her ladies-in-waiting a few years later, Elizabeth was so angry that she sent both Raleigh and his wife to the Tower of London.
It sounds more like a fit of pique than a really serious punishment however. Two months later, Elizabeth freed Raleigh to do a little job for her, dividing up some captured treasure, then sent him back to the Tower again, and then released both him and his wife a few months after that. Raleigh still wasn't in her good books for some time after this, so he went back to travelling and exploring, making the first of two expeditions along the Orinoco river in South America, looking for the fabled golden city of El Dorado.
Sir Walter Raleigh was back in favour with Elizabeth in the last years of her life, but four months after she died, he was in the Tower of London again, imprisoned for plotting against Elizabeth's successor, King James I. He stayed in the Tower for 13 years, before being let out to go off and look for El Dorado a second time.
When Raleigh returned to England the following year, however, King James was persuaded by the Spanish ambassador that he should face the death sentence. While he was abroad, he had deliberately broken a peace treaty between England and Spain by attacking a Spanish outpost. Apparently, Sir Walter Raleigh's last words before his head was chopped off were "Strike, man, strike!"