Who became empress of India following the Sepoy Rebellion?

Queen Victoria formally became 'empress of India' in 1877 though the country went under British control in 1858, i.e. just after so called 'sepoy mutiny'.

In India, sepoy rebellion is referred as India's First War of Independence, even western scholars described the movement as 'national revolt'. It culminated in the dissolution of East India Company's power to control the country, and India became a part of British Raj in 1858.