Actor who played the venal Maryland state governor Clay Davis in the US crime drama The Wire

Many fictional characters are known by their catchphrases. Few are identifiable by a single exclamation alone. Among the exceptions are Lady Bracknell in The Importance of Being Earnest (“A handbag?”) and the venal Maryland state senator Clay Davis, who appeared in all five series of the acclaimed US crime drama The Wire between 2002 and 2008.

Senator Davis, played by Isiah Whitlock Jr, who has died aged 71, was notable for his unique pronunciation of a monosyllabic expletive. On his lips, its central vowel was bent out of shape and stretched as thin as pizza dough: “Sheee-it”.

From Brienne of Tarth in Game of Thrones to the Hot Priest in Fleabag and of course Dr Frasier Crane, we salute the game-changers who boosted later seasons of our favourite series

Welcome. Nice of you to finally join us. Hope it was worth the wait. Yes, sometimes a late addition can improve a drama or comedy so much it becomes hard to imagine the show without them. Not every series gets the casting chemistry spot-on straight away. A select few of our favourite TV characters weren’t even on the show when it launched.

We’ve selected 18 characters whose gamechanging arrival in later seasons lifted the whole show and added to its legacy. Behold the super-subs who came off the TV bench and scored a winner …