Warning: SPOILERS for DC's Legends of Tomorrow season 6, episode 1, "Ground Control to Sara Lance".
The Legends of Tomorrow season 6 premiere saw Sara Lance (Caity Lotz) hilariously insult the Avengers but, ironically, her point of view echoes none other than Tony Stark's (Robert Downey Jr.). In the Marvel Cinematic Universe, Iron Man has been a vocal critic of the Avengers' methods of going into action after some great evil has taken place, and their mutual viewpoints show an interesting connection between the former leader of the Avengers and the Captain of the Arrowverse's Legends.
Sara Lance was abducted by as-of-yet-unnamed aliens in Legends of Tomorrow season 6, but the resourceful ex-League of Assassins member freed herself from her imprisonment with unexpected help from Gary Green (Adam Tsekhman), who was revealed to be an alien himself. Sara freed another prisoner, Spartacus, although the legendary gladiator did nothing to help Lance fight of another alien creature that he freed. Instead, Spartacus boasted that if the creature had killed Sara, he would have avenged her, and she replied, "Being an avenger is stupid. The goal is to prevent death. I am a Preventer." Not long after, Spartacus proved the stupidity of avenging by charging at Kayla - the alien in charge - who promptly killed and ate the gladiator. Clearly, Spartacus didn't grasp the concept and value of being a Preventer instead of an avenger.
Ironically, Tony Stark felt the same way about being an Avenger in the MCU. Although Iron Man once threatened Loki (Tom Hiddleston) - "If we can't protect the Earth, you can be damn sure we'll avenge it" - later on, Stark would feel differently about the value of avenging. Keep in mind that Nick Fury (Samuel L. Jackson) named the Avengers after Carol Danvers' (Brie Larson) Air Force callsign. Tony Stark might have picked a different name for the superhero team based on how he behaved in the Avengers sequels. In Age of Ultron, Tony believed wholeheartedly in preventing another alien attack and he wanted to build "a suit of armor around the world". As Stark explained his plan for Ultron to Bruce Banner (Mark Ruffalo), "We're the Avengers. We can bust arms dealers all the livelong day but that up there... that's the endgame". It's true that Ultron went horribly wrong but Tony's dream of prevention so the Avengers wouldn't have to fight - and thus save lives - was sound.
Tony further articulated how his cries for prevention disastrously weren't heeded at the start of Avengers: Endgame. After he made it back to Earth after failing to stop Thanos (Josh Brolin) on Titan, Stark lashed into Steve Rogers (Chris Evans) and expressed his frustration at the Avengers being split apart years prior: "I said we'd lose. You said, 'We'll do that together too.' Well, guess what, Cap? We lost! And you weren't there. But that's what we do, right? Our best work after the fact? We're the Avengers, not the Prevengers, right?"
Like the Legends, who routinely correct their screw-ups by using time travel, the Avengers also resorted to violating the timeline by using the Quantum Realm to heist the Infinity Stones from their recent history. But Tony Stark and Sara Lance have a fascinatingly similar viewpoint on how a superhero team should react to a crisis - ideally, by preventing them from even happening. Unfortunately, it never works out that way for the Avengers, and certainly not for the Legends, who have a greater history of disasters they had to scramble to undo, but both Iron Man and White Canary share the same basically noble idea.
One more thing Sara Lance and Tony Stark have in common is their willingness to kill their enemies to achieve peace. Sara was trained as an assassin, and the self-styled 'Preventer' even bragged to Spartacus, "We're gonna find out who's flying this ship and we're gonna prevent them from breathing," in Legends of Tomorrow's season 6 premiere. Considering how Tony Stark has no qualms whatsoever about killing his enemies, Iron Man would probably have fit right in with Sara Lance and the Legends of Tomorrow.