盾牌座δ变星 (也称为矮造父变星、船帆座 AI)是一种光度会因为表面在径向上的胀缩和非径向胀缩两种原因造成光度变化的变星。通常表面光度的变化在0.003至0.9视星等，在可见光的变化周期为数小时，虽然振幅和周期的影响可能非常大。这类变星的类型通常是A0至F5的巨星或主序星。

这一种变星的原型是盾牌座δ，它展示在光度上的变化从 +4.60到 +4.79等，周期为4.65小时。其他著名的盾牌座δ变星包括五帝座一(狮子座β)和王良一(仙后座β)。织女星被怀疑也是盾牌座δ变星，但是尚未能证实。

A Delta Scuti variable (sometimes termed dwarf cepheid) is a variable star which exhibits variations in its luminosity due to both radial and non-radial pulsations of the star's surface. The variables are important standard candles and have been used to establish the distance to the Large Magellanic Cloud, globular clusters, open clusters, and the Galactic center. The variables follow a period-luminosity relation in certain passbands like other standard candles such as Cepheids. SX Phoenicis variables are generally considered to be a subclass of Delta Scuti variables that contain old stars, and can be found in globular clusters. SX Phe variables also follow a period-luminosity relation. The recently discovered Rapidly oscillating Ap stars are also a subclass of Delta Scuti variables, found on the main sequence. One last sub-class are the pre-main sequence (PMS) Delta Scuti variables.