What is one supporting role that truly stole the screen every scene they were in?

If not already called out-Herbert Lom in the Pink Panther series.

Jude Law in The Talented Mr Ripley

Probably more films are listed because in a TV series unless they are in a limited series or once off guest star role they will soon become main cast if they are that entertaining on screen.

I watched repeat of 70s series The Roads to Freedom on BBC4 recently. I thought Anthony Higgins in a supporting role was the focus of every scene he was in. Surprised he didnt go onto bigger things.

And in Tinker Tailor Soldier Spy... Bernard Hepton having fun as Toby Esterhaze.

I suppose easier to steal the scene when rest of the cast putting in straight / restrained performances... someone can play off that.

I thought Jessie Buckley's performance in Fargo season 4 was amazing.

Was she not the main start of Sicario?