  The romance between Leonard (played by Johnny Galecki) and Penny (Kaley Cuoco) has faced its fair share of obstacles over the years on the CBS sitcom but arguably none bigger than that of Mandy Chow (Melissa Tang)
 She may have only appeared on-screen once in season nine but Mandy’s impact on their relationship has been felt ever since Leonard’s North Sea expedition in season six of The Big Bang Theory
 So what happened to Mandy and where is actress Tang now?What happened to Mandy Chow? Leonard almost managed to ruin his and Penny’s wedding day when he brought up a kiss he shared with Mandy Chow
 While on an expedition on the North Sea, he shared a drunken kiss with his colleague sometime between the season six finale and seventh’s opener
 When he first told Penny, she said she’d manage to get over the kiss because they weren’t engaged at the time
 However, it proved a lot easier said than done and Penny struggled to come to terms with the fact Leonard and Mandy were still colleagues
      On their honeymoon, Leonard said he “felt guilty every time he saw her”. Penny quickly caught on that he was still in contact with her and was furious they worked at the university together
 Desperate to prove there were no romantic feelings between the two, Leonard spoke with Mandy in season nine, episode two
 The kiss clearly meant as little to Mandy as it did to Leonard as she failed to even remember it
 Mandy even questioned whether or not the pair had slept together.      Soon it became clear Leonard telling Penny about the kiss was down to his own issues
 This prompted a hilarious back-and-forth between the two with Mandy clearly uninterested in Leonard or his problems
 Leonard decided to face his problems with Penny head-on and opened up to her about his issues The pair overcame the hurdle of Mandy Chow and this was the last time fans saw of her
 As she was only credited in a “guest starring” role, there was no reason for Tang to appear beyond the episode – but where is she now?      Eagle-eyed fans have spotted Tang in the Big Bang universe again in CBS spin-off young Sheldon
 However, it isn’t to reprise the role of Mandy once more. Tang instead plays the character of Ms Fenley on Young Sheldon opposite Iain Armitage
 The actor has also gone on to star in Netflix Original series The Komisnky Method and Hulu drama The Act
   
