How would his skills compare to the best actors of today?

There's a reason he has an award named after him Mf; guy's a legend!

Today's actors rely on effects, CGI, technical corrections after the fact and makeup to make themselves unrecognizable. Olivier didn't have those resources. He had to use his own skill to do it and he pulled it off repeatably. That's what makes him one of the greatest actors of any time.

Olivier would, I believe, be considered excellent, even to this day. He was a brilliant performer. He might not make everybody's list, but then, has there ever been a true consensus on "greatest actor" (alive or not)?

He created characters as memorable and realised as Hoffman or Lewis. I'm not sure what you mean by "immerse themselves in their character to the extent that they cannot be recognized" as it relates to a superlative performance. Mark Wahlberg is recognisable as Dignam in The Departed, but it's a fully-crafted character - it's a person I can believe exists. He inhabits that role, just as Olivier inhabited Hamlet or Maxim de Winter.

Every actor works differently, and there are a lot of approaches to creating great work on stage and screen. Olivier worked one way, which got wonderful results. I think his work would have transcended. And to say he didn't have the ability to put on costumes, makeup, and affectations until he was unrecognisable is, I think, quite off the mark.

You have a valid point. I suspect if he were a contemporary of De Niro, Homan, Day-Lewis, etc., he would immersing himself. However, we will never know.

He was an actor of his era. That kind of theatrical acting is considered over the top today. He would look silly in a modern film.

Some people are naturals. He's one of them. I suspect he would have been as revered as Hopkins or Day-Lewis without a doubt.

I’ve seen him play a French Canadian, a Chicagoan, a man blinded late in life, a Jew, a Nazi — he could seamlessly execute every performance. Yes, Mr. Olivier had that ability.