In the course of his career, Robin Williams stepped into many roles, both serious and comedic. One of my favorite is his part-funny, part-serious part in the 1984 movie Moscow on the Hudson, where Williams played a Russian defector, Vladimir Ivanoff, grappling with his new life in the freedom of America.
The movie does a good job of dramatizing the contrast between the grayness and limitation of life in the former Soviet Union, and the bustling, but imperfect freedom of New York, USA in the '80s. The movie's message was very relevant in the mid-80s as the cold war continued, and with Williams as the main character, it becomes a veritable time capsule for that era.
There are some very funny moments, as Williams' character discovers all the strange and contradictory components about life in a free society, such as the abundance of products at a local grocery store, which contrasted strongly with the rationing and limited supply under Communism.
And there are indeed some serious moments, as the ups and downs of freedom and capitalism causes Vladimir to question the good and bad in this society. But, ultimately, the movie is a dramatic account of what is positive in western society, even amidst the imperfections and issues still to be dealt with.