iHeartRadio Music Awards (8 p.m., NBC): Apparently, the TV people believe that we just can't get enough awards shows. Now iHeartRadio joins the fun with an event at the Shrine Auditorium in Los Angeles that showcases the biggest stars and songs of the year -- as determined by fans.
"Vikings" (10 p.m., History): Let's get ready to ruuuuuuuuumble! In the Season 2 finale of this raucous period drama, a final showdown between two leaders is at hand as Ragnar and King Horik (Travis Fimmel, Donal Logue) return to Kattegat. Ragnar has placed his trust in those who have stood by him and now the time has come for new alliances to be made. Katheryn Winnick and Clive Standen also star.
"Portlandia" (10 p.m., IFC): Season 4 of Fred Armisen and Carrie Brownstein's goofy sketch comedy comes to an end with most of the characters -- including guest star k.d. lang -- heading to a feminist retreat in beautiful New Beavertown for the weekend. Jason Sudeikis, decked out in a really big wig, also drops by.
Also on Thursday: