It all depends on why they are studying them. If they are studying them mainly because they want to learn all about monkeys, they are called Primatologists. If they are studying them to learn more about people, they may be anthropologists or psychologists. If they are interested in why monkeys behave the way they do, they are probably behavioral ecologists. If they want to see how monkeys fit into their environment, they are probably ecologists. I could go on, but the big message is that there are lots of reasons to study monkeys and people from different fields of science are interested in them. If you are interested in a career studying monkeys, you can get there from several directions.

Monkeys are primates. Scientists who study monkeys are called Primatologists. Probably there are also many other kinds of scientists who study monkeys such as physiologists and neurobiologists. They would study the physiology and neurobiology and whatever of primates, and you could call them primate physiologists and primate neurobiologists.

You might be surprised to know that many different kinds of scientists study monkeys (also known as primates). Scientists that study their biology (e.g. the type of food they eat, where they live, how many babies they have per year, how many different kinds of species there are) are called primate biologists or primatologists.

Many scientists are very concerned that primates will go extinct soon. Primates often rely on tropical rain forests for their survival and need large areas of undisturbed forest, and the rapid destruction of rainforests worldwide (South America, Africa, Indonesia/Borneo) means that many, many species are now endangered. They are also hunted for food in these areas. The scientists that are studying how to keep these species from going extinct include primate biologists, conservation biologists and tropical ecologists. Scientists that study their social networks (e.g. who's in charge, how groups are formed, how individual primates interact, how they behave when threatened, how they behave in captivity, how they learn) include anthropologists, behavior scientists, psychologists and ethologists (animal behavior scientists). Many of these types of scientists also study human behavior, so there is some overlap.

A famous ethologist who studies gorilla behavior in Africa is Dr. Jane Goodall. Scientists that study primate fossils and try to piece together how primates have evolved over time (including which of their ancestors evolved into to humans) are called anthropologists, paleoanthropologists or archaeologists. A famous archaeologist that studied primate evolution with the hopes of finding clues to human evolution is Mary Leakey.