Ben Burtt asked Fosselius to contribute unusual voices and vocal effects to several Lucasfilm productions, such as the two pilots in "Indiana Jones and the Temple of Doom". He provided the voice of in "" and voiced the sobs of the Rancor Keepers, Malakili and Giran, in "Return of the Jedi". He also contributed to the music score of "Return of the Jedi" and is credited with co-writing the song "Lapti Nek". Additionally, he voiced the "Ack Ack"s in "Mars Attacks!" and was also the voice of Trantor the Troll in "Ernest Scared Stupid".