dˈænjəl kˈæslɚ; fˈoːɹ mˈɑːɹtʃ nˈaɪntiːnhˈʌndɹɪd twˈɛnti sˈɪks fˈoːɹ dʒuːlˈaɪ tˈuː θˈaʊzənd fˈɪftiːn wʌzɐ fɹˈɛntʃ θiəɹˈɛɾɪkəl fˈɪzɪsˌɪst, wˈɜːkɪŋ ɔnðə faʊndˈeɪʃənz ʌv kwˈɔntəm fˈiːld θˈiəɹi ænd ˌɔn nˈɑːŋkˈɑːmjuːɾətˌɪv dʒiˈɑːmətɹi.
Daniel Kastler (; 4 March 1926 – 4 July 2015) was a French theoretical physicist, working on the foundations of quantum field theory and on non-commutative geometry.