Theil may refer to:
Archaic variant spelling of German for 'part' (modern High German "Teil"), for example "Erster Theil etlicher Choräle"
People with surname Theil Anders Theil (1970), Danish football manager Henri Theil (1924–2000), Dutch econometrician Georges Theil (born 1940), French politician Pernille Rosenkrantz-Theil (1977), former member of Danish parliament
See also Theil index, a statistical algorithm used to measure economic inequality Theil–Sen estimator, a statistical linear graph method Theil's U, a measure of nominal association also known as the uncertainty coefficient principle Le Theil, a French commune name Thiel, an etymologically related (and commonly misspelled variant) surname