There is Bertrand Russell, a logician, who had another career as a philosopher as well as an anti-war protestor. He helped publicise what was happening in Vietnam - in fact, according to Paul McCartney of the Beatles, at one point he lived on the same square or street with Russell and he had knocked on his door to introduce himself and Russell proceeded to tell him all about the war. This is, according to Paul McCartney, how the Beatles became involved in the anti-war protest movement, in particularly against the war of aggression by the USA on Vietnam.
Sofia Kovalevskaya was one of the first handful of female mathematicians. She was also a writer, having written a well-received autobiography, A Russian Childhood in where she reveals she met Dostoyevsky as a young woman and did not think much of him.
Likewise, Lewis Carroll, also a logician and who wrote the best-selling Alice's Adventures in Wonderland.
And a special mention for Walter Sisulu, who studied a science degree, but after joining the ANC, was imprisoned several times, and was finally imprisoned on Robbens Island with Nelson Mandela and sentenced to twenty-five years - the same sentence as Nelson. He rose to become the ANC's Secretary-General and Deputy President of the organisation.