Despite the two clubs being located in different cities, the rivalry between them is as fierce as any on the planet.
And, when they go head-to-head again on Sunday, there will be no love lost between the Reds and the Red Devils.
Players that play in the derby, if you can call it that, never forget the occasion and carry their hatred for the other throughout the rest of their career.
Unless you're Michael Owen, of course.
For Wayne Rooney, his loathing for Liverpool was doubled - by the fact he was raised as an Everton fan, played for the blue half of Merseyside and later played for United!
"I grew up an Everton fan, my whole family are Everton fans and I grew up hating Liverpool - and that hasn't changed," he once said.
And as Jurgen Klopp's side were going head-to-head with Manchester City for the Premier League title in 2018/19, the current Derby boss said it would be a 'nightmare' if they won the title.
The good news for Rooney, City were champions that year. The bad news? Liverpool won it the season after.
"I hope Man City get over the line before Liverpool. I couldn't bear to see them win it, it would be a nightmare for any Evertonian," he said, at the time.
Another Scouser, Steven Gerrard, once made the cardinal sin of wearing a United shirt but it wasn't for long - after his dad spotted him and 'went ballistic'.
"A mate of mine owned this [Bryan] Robson top, the old blue-and-white one with dashes on it," the former Liverpool captain wrote in his autobiography.
"We were kicking about on Ironside (the road he grew up on) and I asked him whether I could be Robson for a while.
"I slipped out of my Liverpool shirt, and put the Robson one on."
He continued: "Unfortunately, dad looked out the window and went ballistic.
"'What the hell are you playing at, wearing a Manchester United shirt?' he asked.
"'But dad, it's Bryan Robson's shirt,' I explained.
"Dad couldn't have cared less. 'You should know better,' he said."
If you've watched Sky Sports at any point over the last decade, you will know that Gary Neville isn't too fond of Liverpool,
And he made that abundantly clear back in 2006 when he maniacally celebrated Rio Ferdinand's late winner in front of the travelling Liverpool fans at Old Trafford.
He was fined £10,000 but does he regret it? Not by the sound of things…
He told Sky Sports: "It was worth a 120-match ban!"
Jose Enrique played for Liverpool between 2011 and 2016 and experienced the hatred the Merseysiders and United have for each other first hand.
"I took throw-ins and the Manchester United fans say so much s*** but I wasn't listening to be honest - it's too many people talking to you at the same time," said Enrique, speaking to talkSPORT.com in association with BeMyBet.com.
"They're saying, 'You are s***', things like that. It's hard to pick one phrase because it's many, many people going at you in one second."
Andy Robertson and Trent Alexander-Arnold have that to look forward to on Sunday.