Written and first recorded by Townes Van Zandt (1972).
Also recorded by Emmylou Harris (1977), Hoyt Axton (1977).
Hit version by Willie Nelson & Merle Haggard (MOR #21/C&W #1/CAN #1 1983).
From the wiki: “”Pancho and Lefty” is a song written by country singer and songwriter Townes Van Zandt. Often considered his “most enduring and well-known song,” Van Zandt first recorded it for his 1972 album, The Late Great Townes Van Zandt. Emmylou Harris then covered the song for her 1977 album, Luxury Liner. Also in 1977, Hoyt Axton recorded it on his album Snowblind Friend. The song became a #1 Country hit in 1983 when Merle Haggard and Willie Nelson adopted it as the title track of their duet album Pancho & Lefty. Members of the Western Writers of America chose it as one of the Top 100 Western Songs of All Time.