  In supersymmetric grand unified theories, light higgsino multiplets generally
exist in addition to the familiar chargino/neutralino multiplets of the minimal
supersymmetric extension of the Standard Model. The new multiplets may include
doubly charged states $\tilde\Delta^{\pm\pm}$ and $\tilde\delta^{\pm\pm}$. We
study the properties and the production channels of these novel higgsinos in
$e^+e^-$ and $\gamma\gamma$ collisions, and investigate how their properties
can be analyzed experimentally.
