Lisa (C137)

Lisa was an alien girl who appeared in the episode, "The Whirly Dirly Conspiracy." She was seen playing with her brother at the restaurant where Rick and Jerry are drinking. They have a real weapon they shoot each other with. The restaurant is part of a resort with an immortality shield, making Lisa, her brother, and everyone there immortal.

Background
They may have come from a wealthy family as they are staying at such an expensive resort. Watching the two play kill each other, Jerry disapproves saying such is bad parenting. Rick shrugged it off describing the people who come to the resort as 'rich A-holes'.

Lisa is unfortunately killed when the immortality shield is turned off, at the exact moment her brother shoots her in the head. When Lisa isn't brought back to life, Lisa's brother calls out her name, horrified.