Pekka Lars Kalervo Sammallahti (Inari Sami: Sevtil-Piäkká, May 21, 1947 in Helsinki) is a professor of Sámi languages at the Giellagas Institute at the University of Oulu.
A prolific writer, he has published more than 100 books and articles related to Sápmi and the various Sámi languages.
Sammallahti has also been a driving force in the work done to create official written languages for a number of Sámi languages.
He is a member of the Norwegian Academy of Science and Letters.He is the only brother of photographer Pentti Sammallahti.