The friendship between Captain James T. Kirk (William Shatner) and Mr. Spock (Leonard Nimoy) was a staple of Star Trek: The Original Series and the first six Star Trek films, and there are so many moments that illustrate the bond they shared. As arguably the two most famous Star Trek characters, Kirk and Spock's friendship has stood the test of time. While they have vastly different personalities, their differences complement one another, and they often bring out the best in each other.

Star Trek: Strange New Worlds season 2 will show the earliest stages of Kirk and Spock's iconic friendship, including how they met. But their friendship is a constant through nearly every episode of Star Trek: The Original Series. While they do not always agree, they have an obvious admiration and respect for one another that shines as one of the best examples of male friendship on television and films. Here are 10 of the best moments of Kirk and Spock's friendship.

Related: “Classic Bromance”: Strange New Worlds’ Kirk & Spock Dynamic Teased By Star

10 Kirk and Spock Play Gangster in Star Trek: TOS "A Piece of the Action"

Star Trek Piece of the Action Spock Kirk

The way Kirk and Spock work together and play off of one another in "A Piece of the Action" underlines how good of friends they are. From Spock remarking on Kirk's poor driving skills to their coordinated outfits and accents, Kirk and Spock are clearly having fun during this episode. While many of the moments on this list focus on more serious moments when either Kirk or Spock's life is in danger, this episode represents the moments where the two of them get to have fun. Spock goes along with most of Kirk's schemes and, in the end, he gets just as into the gangster mindset as Kirk does.

9 Kirk's Worry for Spock in Star Trek: TOS "Errand of Mercy"

Star Trek Errand of Mercy Kirk Spock

In "Errand of Mercy," Kirk and Spock visit a neutral planet Organia near the Klingon border hoping to persuade the people there to resist Klingon occupation. When a Klingon ship arrives unexpectedly, Kirk and Spock find themselves trapped on the planet. They disguise themselves and pretend to be traders, but the Klingon leader, Kor (John Colicos), immediately distrusts Spock. Kirk protests strongly when Kor takes Spock away to be interrogated, but Spock is able to resist the Klingon's mind scanner interrogation device. The rest of the episode contains some great banter as Kirk and Spock work together to inspire the inhabitants of the planet to fight back against the Klingons, only to learn the Organians are evolved, super-powerful beings.

8 Kirk Shows How Much He Cares About Spock in Star Trek: TOS "Journey to Babel"

Star Trek Journey to Babel Kirk Spock

The Enterprise is called to transport Ambassador Sarek (Mark Lenard) and his wife Amanda (Jane Wyatt) to a conference, and Kirk is surprised to discover that they are Spock's parents. Spock and his father are not speaking because Sarek does not approve of Spock's decision to join Starfleet. When Sarek suffers a heart attack, Dr. McCoy (DeForest Kelley) needs to use Spock's blood for a transfusion. However, before the surgery can take place, Kirk is injured and unable to command the Enterprise. Spock steps up to command and refuses to relinquish the position to save his father. To allow Spock to help Sarek, Kirk retakes his place as Captain despite his injuries. "Journey to Babel" shows how much Kirk cares about Spock and how much Spock cares about the Enterprise and its crew.

Related: What Happened To Kirk & Enterprise Crew After Star Trek: TOS?

7 Kirk and Spock Have Fun in 1986 in Star Trek IV: The Voyage Home

Spock and Kirk in the '80s in Star Trek IV: The Voyage Home.

In Star Trek IV: The Voyage Home, Kirk, Spock, and the rest of the crew must travel back in time to 1986 San Francisco to rescue a couple of whales. The crew splits up and Kirk and Spock go in search of these whales, resulting in a rather hilarious jaunt across San Francisco. From misusing profanities to Vulcan-nerve-pinching annoying bus passengers, Kirk and Spock fail at their attempts to blend in, but they do seem to be having a lot of fun. By this point in their story, Kirk and Spock have saved each other's lives multiple times and Kirk has even brought Spock back from the dead. After so many serious moments, it's nice to see Spock and Kirk get back to having fun and saving the galaxy.

6 Kirk's Defense of Spock in Star Trek: TOS "Balance of Terror"

Star Trek Balance of Terror Spock Kirk

The Star Trek: The Original Series season 1 episode "Balance of Terror" introduces the Enterprise crew to the Romulans, who turn out to be an offshoot of the Vulcans. One of the officers on the bridge begins to suspect Spock may know more about the Romulans than he admits. Kirk defends his friend and has no room for the man's prejudice, telling him to "Leave any bigotry in [his] quarters. There's no room for it on the bridge." While Kirk may sometimes poke fun at Spock's Vulcan tendencies, he clearly has a lot of respect and love for him. Captain Kirk has a lot of great episodes and this is one of his best, in part because his trust in Spock never wavers.

5 Kirk Calls Spock His Brother in Star Trek V: The Final Frontier

Star Trek V Final Frontier Spock Kirk

At the end of Star Trek V: The Final Frontier, Spock laments the loss of his half-brother Sybok (Laurence Luckinbill). Kirk responds that he "lost a brother once" before turning to Spock and saying: "But I was lucky, I got him back." McCoy replies: "I thought you said men like us don't have families." Kirk answers: "I was wrong." This scene underlines the brotherly relationship that these three men have formed over the years, and especially highlights the friendship between Kirk and Spock. In Star Trek: The Original Series, Kirk kept many of his crewmembers at a distance, but by the time of the films, he is more willing to express how much he cares about his friends.

4 Spock's Fear for Kirk in Star Trek: TOS "The Devil in the Dark"

Star Trek Devil in the Dark Kirk Spock

The TOS season 1 episode "The Devil in the Dark" finds Captain Kirk and his crew searching caverns for a dangerous creature that has killed several men. At first, Kirk does not want Spock to join in the search for the creature, but Spock convinces him to change his mind. As they being their search, Spock wishes to simply subdue the beast, but when a cave-in traps Kirk with the creature, Spock urges him to kill it. Though Spock would rather not kill the creature, he would much rather the creature die than Kirk. At various times throughout this episode, Spock displays clear fear for Kirk's safety, going from calling him Captain to shouting for him as Jim.

3 All of Star Trek III: A Search for Spock

Star Trek III Search for Spock

While Spock is absent for the majority of the third Star Trek film, the entire story revolves around Kirk's determination to find Spock and bring him back to life. The whole of Star Trek III: The Search for Spock acts as a love letter of sorts to the character of Spock. Kirk not only disobeys direct orders and risks his own life to save Spock, but also destroys the Enterprise in the process. Kirk is willing to risk everything for even the most remote chance that Spock can be brought back. The most heartwarming scene comes at the end of the film after Spock has been restored. Though his memories are fragmented and slow to return, one of the first things Spock remembers is his friend's name. Kirk tells Spock: "You saved the ship. You saved us all. Don't you remember?" Spock thinks about it for a minute, and his expression shifts to one reminiscent of the old Spock before he replies: "Jim. Your name is Jim."

2 Spock's Relief at Seeing Kirk Alive in Star Trek: TOS "Amok Time"

Star Trek Amok Time Kirk Spock

While it may seem odd to include an episode where Spock believes he killed Kirk on this list, Spock's face when he realizes Kirk is still alive says it all. Early in "Amok Time," Kirk and McCoy realize that something is off with Spock, but he refuses to tell them what it is. Despite this, Kirk trusts Spock when he says he needs to get to Vulcan. When Spock finally does tell Kirk what is happening, Kirk disobeys Starfleet's orders in order to get Spock to Vulcan in time to save him. Later, when Spock believes that he has killed Kirk, he is clearly distressed and offers to resign from Starfleet. One of Spock's best moments comes when Dr. McCoy reveals that Kirk is alive and the look on Spock's face radiates relief and pure joy.

1 Spock and Kirk's Goodbye in Star Trek II: The Wrath of Khan

Kirk says goodbye to Spock in Star Trek II The Wrath of Khan

Perhaps the most well-known moment of friendship between Kirk and Spock comes at the of Star Trek II: The Wrath of Khan. Spock sacrifices himself to save the Enterprise and the lives of his friends. As he dies, he utters the famous line: "I have been and always shall be your friend." This, along with Kirk's speech at Spock's funeral serves to illustrate just how close the two friends were. Kirk ends his speech with the lines: "Of my friend, I can only say this: of all the souls I have encountered in my travels, his was the most human." What was once an insult to Spock is said here with only love and respect. Though Spock would return in later movies, his death remains one of the most heartfelt and heartbreaking Star Trek deaths. Because of all of these examples and so many more, Kirk and Spock's friendship across Star Trek: The Original Series and its movies remain one of the best examples of male friendship on screen.