‘The Big Bang Theory’/ ‘Young Sheldon’

After 12 seasons, the two-part finale of the hit comedy finds the gang taking a big trip together as everyone finds out important things about themselves and each other, with Sheldon and Amy awaiting big news, Penny and Leonard keeping secrets and Koothrappali making a new friend as the gang travels into an uncharted future, 8 p.m. Thursday; followed by the season-two finale of the spinoff “Young Sheldon,” (renewed for two more seasons), with Leonard, Penny, Howard, Raj, Amy and Bernadette as kids, 9 p.m., followed by “Unraveling the Mystery: A Big Bang Farewell” retrospective, 9:30 p.m. Thursday on KIRO.

Also on Thursday

“Grey’s Anatomy,” 8 p.m. (KOMO): Season 15 finale, renewed for two more seasons; as fog begins to cover Seattle, the doctors must navigate personal complications.

“Superstore,” 8 p.m. (KING): Two-part season-four finale, series renewed; Amy and Dina visit corporate to fix problems caused by Sandra’s misguided activism; when the company’s tactics get extreme, everyone bands together to save one of their own.

“Station 19,” 9 p.m. (ABC): Season-two finale, series renewed; the team heads to Los Angeles to help battle a deadly wildfire; Andy and Sullivan continue to explore their attraction to each other.

“Brooklyn Nine-Nine,” 9 p.m. (KING): Two-part season-six finale, series renewed; desperate circumstances call for desperate measures, as Jake, Holt, Amy, Terry, Rosa and Charles must ally themselves with old enemies.

“Law & Order: Special Victims Unit,” 10 p.m. (KING): Season 20 finale, renewed for a record-setting 21st season; the team suspects Rob Miller is behind a teenager’s mysterious death.

“For The People,” 10 p.m. (KOMO): Series finale, canceled after two seasons; Jay asks the team for help after his parents and other voters are illegally intimidated at their polling place.

“S.W.A.T.,” 10 p.m. (KIRO): Season-two finale, series renewed; the Emancipators hold a livestream kangaroo court to publicly execute city politicians; Deacon prepares to receive one of the LAPD’s highest honors.

“Better Things,” 10 p.m. (FX): Season-three finale; Sam searches and takes a breath.

Madeline McKenzie: mmckenzie@seattletimes.com. Program times may vary depending on your cable provider or service.