Magnus' toughest opponent

According to Magnus' wikipedia page, he has +0-3=3 in classical games vs. Ian Nepomniachtchi.
Right!But including blitz and rapid its +3-3=8

Giri-Carlsen: +5-7=21
nice try
Including blitz and exhibition
I stand corrected as it looks like chessgames.com has updated their database. However, your total is still wrong: +6-5=22 (i.e. +1 for Carlsen) Given that they have played 33 games and Magnus only has +1, I'd say Giri has been a pretty tough nut for him to crack.
Especially when you compare him to other active members of the 2800+ club:
Carlsen-MVL: +18-6=16 (+12)
Carlsen-Nakamura: +33-14=38 (+19)
Carlsen-Kramnik: +20-12=29 (+8)
Carlsen-Anand: +24-18=61 (+6)
Carlsen-Aronian: +25-19=54 (+6)
Carlsen-So: +10-2=11 (+8)
Carlsen-Mamedyarov: +18-3=12 (+15)
Carlsen-Caruana: +20-11=17 (+9)
He has only played 13 games against Nepo with an even score, but all of Nepo's wins were before 2011 (he has gone almost 7 years without a win against Magnus).
Given those results, Magnus seems to have the most trouble beating Giri. So, nice try?
Oh you're right

Seems like it's Kasparov(+2 against Magnus)but since their last game was played in 2005, it doesn't count

Svidler has +2=1=10 vs. Carlsen in classical games. His last win was in the 2013 Candidates', and since then they have only played 2 classical games, both of which were drawn.
Including blitz and exhibition games, Carlsen has +11-7=19.

Carlsen has said that Aronian is his toughest opponent. But what does he know?
Of course he said that. He doesn't want to make Giri's head any bigger than it already is!
Lol

I think Carlsen himself should know best who gives him the toughest time, and he did say Aronian. Also, macer75, how long did it take you to come up with all those Wesley puns?

I think Carlsen himself should know best who gives him the toughest time, and he did say Aronian. Also, macer75, how long did it take you to come up with all those Wesley puns?
Not so long...
Honestly, the puns were just from the top of my head. Other people here have probably come up with better ones.
Who is/was Carlsen's toughest opponent ever? Who has/had the highest head to head score against him?