Who was next in line to the throne after Henry viii?

After Elizabeth I (otherwise known as "The Virgin Queen" for she never married) died in 1603, James I became King of England. He'd already been King of Scotland for 36 years upon her death and was related to Elizabeth I through her father's (Henry VIII) sister Margaret's daughter, Mary, Queen of Scots, she (Mary) being his mother. He inadvertently became next in line for the throne after Elizabeth, and though, throughout his life tried to unite England and Scotland was unsuccessful among other things during his reign which ended with his death in 1625.