The Biggest and Best Guest Stars on 'This Is Us' So Far

This Is Us was NBC's runaway hit show back in 2016 and, four years later, it's still the tear-jerking, beautiful saga it always was. But, over the course of these four years, it's also built up an impressive cast. 

Aside from the main cast and recurring characters, it's also pulled in some rather big named guest stars. Here's the list of the biggest guest stars that have appeared on This Is Us so far. 

Keep in mind, this is only the list of guest stars who are supplemental to the plot and not major recurring characters. Meaning, even though I love Jennifer Morrison and Asante Blackk and am psyched they're on the show, they don't fall under that category as they appear too often and are too central to the plot.

The TV personality is the first person on this list who plays himself, but he isn't the last one. Mario is seen discussing Kevin (Justin Hartley)'s unfortunate on-set meltdown in Season 1.

Another one who plays himself, Alan Thicke was playing Alan Thicke guest starring on The Manny during Kevin's public meltdown in Season 1.

Funny man Brad did not have a particularly funny task when he was charged with negotiating Kevin's exit from The Manny during Season 1.

Television icon Katey Sagal appeared early in Season 1 as Kevin's agent.

Recognizing Kevin, the TV host steps in when he sees him and Randall (Sterling K. Brown) fighting in Season 1.

The Emmy nominee played Randall's coworker. Randall was the one who talked him out of taking his life.

The Golden Globe winning actress and model was in Season 1 and then reappeared in Season 2, where she dated and then married Dr. K (Gerald Lee McRaney).

The journalist and TV personality appears during Season 1 thanks to a dream sequence in which Kevin has a recurring nightmare that he's having a horrible interview with her.

The actor and director is yet another one who played himself on the show. When Ron sees Kevin's play, he offers to send him a script for a new movie he was producing during Season 1.

The 80s starlet played one of Kate's clients in Season 1.

Elizabeth's role toes the line between guest star and recurring, but we'll include her here anyways. The TV and film veteran played Rebecca (Mandy Moore)'s mother.

The That 70s Show star played a social worker who worked with Randall and Beth (Susan Kelechi Watson) throughout Season 2.

Another one who plays himself, Sylvester Stallone plays Sylvester Stallone in a movie with Kevin in Season 2.

You might not recognize his name or face right away, but Brian has been a top producer in Hollywood for over 40 years. He appears in Season 2 as the producer of Kevin's movie.

The Shondaland and Broadway favorite played a psychologist in Kevin's rehab in Season 2.

The SNL star played a resident in Randall's biological father, William's old apartment building in Season 2.

The TV veteran played a Vietnam veteran in Season 3, who Kevin visits looking for answers about Jack (Milo Ventimiglia)'s time serving.

Mo plays a younger version of Charlie's character in flashback scenes in Season 3.

The House actor appears as Malik (Asante Blackk)'s father in Season 4.

Marsha plays Malik's mother in Season 4.

The Revenge star plays Cassidy (Jennifer Morrison)'s ex-husband in Season 4.

The West Wing star plays Rebecca's father in Season 4.

The director plays himself as a director of one of Kevin's movies in Season 4.

The Psych star appears in Season 4 as Kate and Toby's new neighbor.

The singer serenades Kevin and his date during an ill-fated evening in Season 4.

The One Tree Hill actress is the date getting serenaded during that painful evening in the Season 4 midseason premiere.