Christopher Nolan
Having made some of the most influential and popular films of his time, Nolan's work has been as "intensely embraced, analyzed and debated by ordinary film fans as by critics and film academics". Several of his films have been regarded by critics as among the best of their respective decades, and according to "The Wall Street Journal", his "ability to combine box-office success with artistic ambition has given him an extraordinary amount of clout in the industry." In 2016, "Memento", "The Dark Knight", and "Inception" appeared in BBC's 100 Greatest Films of the 21st Century list. In the following year, five of his (then nine) films featured in "Empire" magazine's poll of "The 100 Greatest Movies". Nolan has been described as "American cinema's most experimental blockbuster auteur" and a "franchise unto himself."
Christopher Nolan
Geoff Andrew of the British Film Institute and "Sight & Sound" magazine, called Nolan "a persuasively inventive storyteller", singling him out as one of the few contemporary filmmakers producing highly personal films within the Hollywood mainstream. He also pointed out that his films are as notable for their "considerable technical virtuosity and visual flair" as for their "brilliant narrative ingenuity and their unusually adult interest in complex philosophical questions". David Bordwell observed that Nolan is "considered one of the most accomplished living filmmakers," citing his ability to turn genre movies into both art and event films, as well as his box office numbers, critical acclaim, and popularity among cinemagoers. In 2008, film critic Philip French deemed Nolan "The first major talent to emerge this [21st] century", while "Forbes" called him "one of the most successful and acclaimed filmmakers of our time" in 2015. Film critic Mark Kermode complimented the director for bringing "the discipline and ethics of art-house independent moviemaking" to Hollywood blockbusters, calling him "living proof that you don't have to appeal to the lowest common denominator to be profitable". "The Observer" described Nolan as a "skilful, stylish storyteller, capable of combining the spectacle of Spielberg with the intellectual intricacy of Nicolas Roeg or Alain Resnais". Mark Cousins applauded the director for embracing big ideas, "Hollywood filmmakers generally shy away from ideas — but not Christopher Nolan". Scott Foundas of "Variety" declared Nolan "the premier big-canvas storyteller of his generation", while Justin Chang of the "Los Angeles Times" called him "the great proceduralist of 21st century blockbuster filmmaking, a lover of nuts-and-bolts minutiae."
Sathish Kalathil
Sathish Kalathil is an Indian film and documentary director and producer in Malayalam. He is also story writer, and lyricist. His experimental works are well known and appropriately discussed in Malayalam Cinema industry and his debut movie Jalachhayam (2010) was well discussed according to its experimental approach. His first film was Veenavaadanam (2008), an experimental documentary about art (painting). In 2012, he directed Laloorinu Parayanullathu, a social committed documentary film about municipal solid waste.

Question: Are Christopher Nolan and Sathish Kalathil both film directors?
Answer: yes