Throughout 12 seasons, fans have seen Sheldon Cooper get into his fair share of disagreements. It doesn't matter if it was with his mom or Stephen Hawking himself, Sheldon would defend his logic to the end. His intelligence is what separated him from the rest of humanity but it's also what got him into trouble.
Sheldon doesn't intend on having rivalries (as he doesn't understand how people could disagree with him) but it happened throughout The Big Bang Theory's 12 seasons. To see a ranking of his 10 best rivalries, keep scrolling!
Tam
Tam's name was never brought up in The Big Bang Theory until season 12. As it turned out, Tam was Sheldon's closest friend growing up. The two promised to move to California together but only Sheldon followed through. Tam decided to stay back in Texas, which upset Sheldon greatly. Sheldon decided to swear off Tam and never speak of him again.
If it weren't for Leonard and co., Sheldon wouldn't have seen Tam again. At first, Sheldon wanted nothing to do with Tam. But when he found out Tam had no idea that Sheldon was even mad at him, things changed. The two slowly became friends again by the end of the episode.
George Cooper Jr.
George Cooper Jr. is Sheldon's older brother. Sheldon brought up his brother a few times in TBBT before fans were introduced to him. According to Sheldon, George (who was named after their father) drank a lot, made forts that Sheldon couldn't enter, and even referred to him as a "mouth-breather." The two were never on good terms.
When it came time for Amy and Sheldon's wedding, Sheldon was practically forced to visit George and mend their relationship. According to Geroge, he was mad at Sheldon for ditching the family for a better future when they were in tough times. It was obvious there was a lot of baggage between the pair but they eventually put their differences aside for the big day.
Wil Wheaton
Before Wil Wheaton became a friend in the group, he was just another Star Trek actor who everyone idolized. Except for Sheldon, of course. In the beginning, Sheldon despised Wil Wheaton because he was a no-show to an event Sheldon was excited for as a child. During an epic battle of Mystic Warlords of Ka'a, Sheldon went against Wil to get back at him for canceling that meet-and-greet so many years before.
As fans know, Wil lied to Sheldon that he couldn't go because his grandmother passed away. Sheldon felt so bad for Wil that he let him win, but as he found out, it was all a lie. Wil only said that to win. Their rivalry went on for a short time before eventually becoming close friends.
Barry Kripke
Barry Kripke is one of those co-workers Sheldon doesn't respect but tolerates. Sheldon doesn't find Barry intelligent but often wants what he has.
The two were forced to work together in "The Cooper/Kripke Inversion," which brought them closer together but Sheldon often judges his entire presence. The two eventually learn to agree to disagree with each other and become acquaintances. Kripke was even invited to Sheldon's wedding!
Howard
Howard is one of those friends who irritated Sheldon the most. However, the feeling was mutual, as Howard couldn't stand Sheldon either. Sheldon refused to respect Howard's education at MIT and his profession as an engineer. Likewise, Howard couldn't stand how pompous Sheldon was.
If anything, Howard was just as smart as Sheldon. The two went head-to-head for years. Even when there was a tender moment between the two it was never enough to fully change their friendship.
Dr. Pemberton & Dr. Campbell
When Sheldon and Amy came together for their Super-Asymmetry theory, Dr. Pemberton and Dr. Campbell were introduced after confirming their theory. What rubbed Sheldon the wrong way is that the two physicists confirmed it by accident. To make matters worse, those at Fermi-Lab and the university could only nominate three individuals for the Nobel Prize, meaning Amy would get the boot, as she was a neuroscientist.
Dr. Pemberton and Dr. Campbell were eventually dropped from consideration after a plagiarizing scandal tarnished their name. Seeing Amy and Sheldon get so fired up at two people who just wanted their name in lights was fun to see as viewers.
Dr. Gablehauser
Dr. Gablehauser lasted two seasons and never seemed to be on Sheldon's good side. As the head of the physics department, he's the one who brought Dennis Kim to campus and fired Sheldon in "The Luminous Fish Effect."
Sheldon didn't respect Dr. Gablehauser because as the head of the physics department, he hasn't done any real research in 25 years. Furthermore, Dr. Gablehauser is typically the one who had to break things up between Leslie Winkle and Sheldon, making Sheldon despise both of them.
Dennis Kim
Just in case there were any fans out there who thought Sheldon wouldn't go after a child in the name of science, think again. Dennis Kim was the 15-year-old North Korean genius who came to Caltech University on a tour.
As one of the best schools for physics, Dr. Gablehauser wanted Sheldon and Leonard to make a good impression on Dennis Kim; but as we all know, Sheldon's jealousy was never going to allow that.
Things only got worse when Dennis judged String Theory. From there on out, he and Leonard did everything they could to deter Dennis from Caltech. To distract this 15-year-old from stealing their careers, they introduced him to beautiful women, which was distracting enough to make him lose interest in the university (much to Sheldon's delight).
Leslie Winkle
Leslie Winkle and Sheldon Cooper never got along throughout the show's entirety. As an experimental physicist who worked closely with Leonard, Sheldon didn't respect Leslie or her work. As a female, Sheldon said some sexist comments to Leslie about focusing on child-bearing instead of the sciences, which made Leslie's hatred for Sheldon rage.
Sheldon was beyond annoyed when Leslie began seeing both Leonard and Howard. She also replaced him in "The Physics Bowl Quiz." Leslie rarely called Sheldon by his name and referred to him as "dumbass" more often than not, which made this TV rivalry hilarious.
Priya
Priya is that one woman in Sheldon's life who he couldn't run from. As the sister of Raj and girlfriend of Leonard, how could Sheldon escape her? To make matters worse, Leonard and Priya got pretty serious, forcing her to spend more time with their friend group. Sheldon hated that Priya was a very intelligent lawyer who used her knowledge to diminish Sheldon's roommate agreement.
What's fun for viewers is that Priya also despised Sheldon, making the two of them combative when they were in scenes together. Sheldon finally got his way when Priya moved back to India and broke up with Leonard, but it was fun to see them go head-to-head throughout their relationship.