1. Alan Turing
Alan Turing (June 23, 1912 — June 7, 1954) was a British mathematician and logician who made major contributions to mathematics, computer science, and artificial intelligence. He developed the Bombe, a machine used to decode the Enigma code used by Germany in World War II. In 1950, he proposed the Turing Test, a method of inquiry used for determining if a computer is capable of thinking like a human. This test later became the backbone of many modern artificial intelligence advances.
2. Ada Lovelace
Ada Lovelace (December 10, 1815 — November 27, 1852) was an English mathematician who a program for the prototype of a digital computer. She has been called the first computer programmer. She described an algorithm for the Analytical Engine that could compute Bernoulli numbers, sequences of rational numbers which occur frequently in analysis. Far before smart computers were created, she conceptualized the potential of computers and even tried to implement it on the Analysis Machine, as mentioned in her notes.
3. Tim-Berners Lee
Tim-Berners Lee (December 10, 1815 — November 27, 1852) is a British computer scientist, generally credited as the inventor of the World Wide Web. He established the World Wide Web at the Massachusetts Institution of Technology’s Laboratory for Computer Science in 1994. During his time at CERN (European Council for Nuclear Research) in 1980, he developed a program for himself called Enquire that could store information in files. This technique is known as hypertext, something used in almost every website (even this one! The sources are hypertexts since they lead you to a different place when you click them).