Jack (card)
Anthropomorphic jacks of spades and hearts
A jack or knave was a playing card featuring a man in the traditional or historic aristocratic or courtier dress.
Two artificial knaves who appeared as knights, characters from Alice Through the Looking Glass, were alongside the Queen of Hearts as they chased the landing party from the USS Enterprise during its second visit to the Shore Leave Planet in 2269. (TAS: "Once Upon a Planet")
As Worf was preoccupied with his loss to Counselor Deanna Troi in a poker game in 2368, he told Geordi La Forge that he had jacks and eights, she bluffed him with a pair of sixes. (TNG: "Ethics")