Herbert Jansch (born 3 November 1943), known as Bert Jansch, is a Scottish folk musician and founding member of the band Pentangle. He was born in Glasgow and and came to prominence in London in the 1960s, particularly as an innovative and accomplished acoustic guitarist, but also as a singer and songwriter. He has recorded at least 25 albums and has toured extensively starting in the 1960s and continuing into the 21st century.

Jansch was a leading figure in the British folk music revival of the 1960s, touring folk clubs and recording several solo albums, as well as collaborating with other musicians such as John Renbourn and Anne Briggs. In 1968, he joined the band Pentangle, touring and recording with them until their break-up in 1972. He then took a few years' break from music, returning in the late 1970s to work on a series of projects with other musicians. He joined a reformed Pentangle in the early 1980s and remained with them as they evolved through various changes of personnel until 1995. Since then, Jansch has continued to work as a solo artist.

His work has influenced such artists as Paul Simon, Johnny Marr, Bernard Butler, Jimmy Page, Nick Drake, Graham Coxon, Donovan and Neil Young. He has received two Lifetime Achievement Awards at the BBC Folk Awards: one, in 2001, for his solo achievements and the other, in 2007, as a member of Pentangle.