John Bentley
John Bentley was a human scientist living in the late 20th century.
In 1980, while his mind was occupied by worries about the Iran crisis, he made a mistake while experimenting with an X-ray machine and accidentally discovered a method of time travel. Intent on escaping the perilous Atomic Age and into the past, he worked for weeks building a time cabinet, and eventually managed. In quick succession, he visited the 18th century, the year 1588, the 14th century and finally the late Roman Empire, in all cases blundering head-first into mortal danger and narrowly escaping with his life back into the time machine. He eventually returned to 1980, chastened by the experience, accepting that every era of human history has its own horrors and there was no sense in trying to outrun them, instead of working to overcome them just as all those previous evils had been overcome by his ancestors. This story became known to the Fourth Doctor, who collected it as one of his "time tales". (COMIC: Dr. Who's Time Tales