Arshak B. Petrosian (December 16, 1953) is an Armenian Grandmaster of chess (1984) and FIDE Senior Trainer (2004).
Played in the Chess Olympiads of 1992 (team bronze medal) and 1996, in the World Men's Team Championship of 1993 and in the USSR Championship of 1985. Petrosian won the Armenian Chess Championship in 1974 and 1976 (tied with Vanik Zakarian and Gagik Akopian).
Other results include: =1st at Yerevan 1980; 1st at Albena 1980; 3rd at Lvov 1981; =1 at Bagneux 1981; =1st at Novi Sad 1983; 1st at Yerevan 1984; =7th at Yerevan 1986; =1st at Tunha 1987; =2nd at Budapest 1987; =3rd at Dortmund 2000 (B-tourn).
He is Armenian National Men's Team coach and father-in-law and second of Hungarian grandmaster Peter Leko. In 2004, Petrosian was awarded the title of FIDE Senior Trainer. In 2006, he was awarded the Khorenatsi medal and in 2009 Botvinnik Medal (by FIDE).