Roman Hoffstetter (born 24 April 1742, in Laudenbach, near Bad Mergentheim, Holy Roman Empire; died: 21 May (Baker's) or June (New Grove 2nd) 1815, in Miltenberg-am-Main, Germany; alternative spelling Romanus Hoffstetter) was a classical composer and Benedictine monk who also admired Joseph Haydn almost to the point of imitation. Hoffstetter wrote "everything that flows from Haydn's pen seems to me so beautiful and remains so imprinted on my memory that I cannot prevent myself now and again from imitating something as well as I can."
In 1965, the musicologist Alan Tyson (with H.C. Robbins Landon) published the finding that the entire set of six String Quartets long-admired as Haydn's Op. 3, including the Andante cantabile of No. 5 in F Major known as Haydn's Serenade, were actually by Roman Hoffstetter. Further discoveries have purported to establish Hoffstetter's authorship of the first two of the six quartets, but not the other four.
thumb|Haydn (Hoffstetter) String Quartet No. 5 in F Major Op. 3, 2nd Movement - aka "Serenade": Andante Cantabile. Written by Roman Hoffstetter but commonly attributed to Joseph Haydn
Little is known about his early training or life, though it is likely that he came from a musical family. He was a twin; the other was Johann Urban Alois Hoffstetter, who became director of the Franconian province of the Teutonic Order and also a small-time composer. Hoffstetter took his vows as Pater Romanus at Amorbach Abbey on 5 June 1763, and was ordained a priest on 10 September 1766.