Konrad Zuse was one of the first, if not the first, computer scientist to complete a functioning computer. Unfortunately, there's a good chance you haven't heard of him. Zuse lived in Germany in the late 1930s, which wasn't ripe ground for international collaboration. It also wasn't a great place for long-term records storage.
Born in 1910 in Berlin, Konrad enjoyed art and building construction, and studied civil engineering at the Technical University in Berlin. Although there was no such thing as "computer science" at the time, by today's thinking, one would expect an early computer scientist to be drawn to electrical engineering, or perhaps "pure" mathematics or physics. Like his contemporary, Albert Einstein, or a handful of more modern computer pioneers, he didn't really fit into traditional college education, and ultimately pursued something quite different. Perhaps this inability to fit in is what allows people like this to do really extraordinary things.
Also similar to, say, early Apple pioneers, Zuse started his work in a non-traditional location. While "mere mortals" like Steve Wozniak at least stuck to a garage where they could be safely banished, Zuse set up shop to make his pioneering Z1 computer in his parent's living room. Although certainly inconvenient at the time, what Zuse came up with was nothing short of revolutionary: the first computer. It was able to execute instructions at 1 hertz off of a punched tape reader using only mechanical relays controlled by an electric motor.
Unfortunately, and perhaps unsurprisingly, the original Z1 was destroyed by Allied bombardment in 1943 along with all construction plans. Zuse had by this time moved on to "mere" electrical computers. He first produced the Z2, a prototype using only 200 relays. After demonstrating this technology, the Z3 was developed in 1941, and used in aircraft development before World War II was over.
Zuse would go on to be involved in the fledgling computer science industry, founding the Zuse KG company. He was eventually recruited by IBM in 1947 as an employee, but according to Zuse's autobiographical account they were only interested in his patents. Presumably because of this, he declined employment the company.
Whatever the full scale of their interest was, IBM was definitely interested in his patents, and backed the Triumph company in a suit against him. Unfortunately for Zuse, this suit would eventually end in IBM's favor in 1967. In debt, and now without patent protection, Zuse sold his company that year to Siemens AG.
This seems like a sad ending to one of computing's pioneers, however, there is a significant silver lining. In 1986, presumably unsaddled with the responsibility of running Zuse AG, he decided to reconstruct the Z1 computer. Amazingly, without the original plans, he was able to finish it in 1989 at nearly 80 years old. This magnificent work of engineering now sits in the German Museum of Technology in Berlin. If you happen to be in Berlin for whatever reason, this exhibit should be high on any technology buff's list of things to see.