Star Trek: Q

[Maverick]

 The villain that launched the Next Generation of Star Trek, Q (and his cohorts from the Continuum) appeared across 3 Trek series:

 "Encounter at Farpoint" (TNG)

 "Hide and Q" (TNG)

 "Q Who?" (TNG)

 "Deja Q" (TNG)

 "Qpid" (TNG)

 "True Q" (TNG)

 "Tapestry" (TNG)

 "Q-Less" (DS9)

 "All Good Things..." (TNG)

 "Death Wish" (VOY)

 "The Q and the Grey" (VOY)

 "Q2" (VOY)

 

 Q started off as an interesting antagonist with a sinister edge.   Unfortunately, the edge slipped away in each successive appearance (some more than others)  until by the end he was more like wacky Uncle Arthur than an omnipotent being toying with a new curiosity.    

[John Potts]

Possibly might want to include The Squire of Gothos (TOS, 1.18), who provided the inspiration for Q (and in non-canonical supplementary material is revealed as member of the Q Continuum)

[Maverick]

 Interestingly, everyone involved in Encounter at Farpoint thought Roddenberry was crazy to add a character that was so close to one he had already done before.   He was adamant that the audience would like the character and kept him in.   I think the success of the character had as much to do with De Lancie's portrayal as the writing.    

[SVNBob]

On 4/25/2020 at 5:15 PM, John Potts said:

Possibly might want to include The Squire of Gothos (TOS, 1.18), who provided the inspiration for Q (and in non-canonical supplementary material is revealed as member of the Q Continuum)

The non-canon novel in question.  (Caution: Spoilers ahead.)