His match with Eddie Guerrero at WCW's Halloween Havoc 1997 is a classic and arguably put Mysterio on top of the company's Cruiserweight Division for the remainder of WCW's existence. (It also did wonders for improving Eddie's status as an Ensemble Darkhorse until he jumped ship to WWE in 2000.)
Mysterio's match with Chris Jericho at WWE's The Bash 2009 saw him pulling out spots he hadn't done since 2002. WWE itself ranked it the #2 match of the year (behind only Shawn Michaels vs. The Undertaker).
2002 was Rey Mysterio's debut year in the WWE. Let's briefly run down why it was awesome:
He has one of the most memorable debuts by jumping off the top of a steel cage.
Mysterio and Angle went out on the next SmackDown and had a repeat performance that was even better.
Rey continues the feud with Angle, who wasn't taking him seriously because he was focused on his other Rival, Chris Benoit; the trio has a Triple Threat match which Mysterio wins.
Mysterio goes on to No Mercy to have a tag match with partner Edge against reluctant tag team partners Chris Benoit and Kurt Angle for the new SmackDown-only tag team championships, which was an instant classic (and hailed as Match of the Year by many a wrestling critic).
On the next SmackDown, the two teams face off again, this time with a Two-Out-of-Three Falls stipulation; that match was just as good as the No Mercy effort.
Mysterio and Edge defend those titles against Los Guerreros (Eddie and Chavo) and the Angle/Benoit team at Survivor Series. All six of the "SmackDown Six" in the ring together? If that isn't a classic, then what is?
Rey's win at Wrestlemania 22, scoring him the World Heavyweight Championship. All in memory of Eddie Guerrero. Dreams do come true.
In late 2010/early 2011, Mysterio suffered a similar injury as The Undertaker and was told by WWE doctors and trainers to stop wrestling--even though the company needed him to tour. Instead of taking a break like 'Taker, Rey went on tour, further aggravating the injury while supporting the company. As a reward for his commitment to the job, WWE gave him the opportunity to run a program with anyone of his choosing (since he wasn't in a major storyline at the time). He chose Cody Rhodes--and helped elevate Rhodes to near-main-eventer status based on the strength of their impromptu program.
While this wasn't televised, a face-off between Rey and fellow high-flying luchadore Sin Cara actually occurred during a battle royal. This was something that everyone has been wanting to see since Sin Cara debuted on WWE. This delivered. Everyone in the ring completely stopped to watch the incredible moves the two were pulling off. Kofi Kingston's reactions said it all.
...until The Miz threw Sin Cara over the top rope to a wall of booing.