Nadarajah Selvarajah is a Sri Lankan librarian, writer and bibliographer. Selvarajah has written more than 43 books until June 2017. So far he has compiled 11 volumes of Nool thettam - a bibliography of Tamil books. He has also compiled a bibliography of Tamil publications in various countries such as Malaysia and Singapore. He has also compiled a volume of Noolthettam in English, which contains English publications of Sri Lankan Tamils.