While Darth Vader and Jedi Master Yoda never fought in the official Star Wars canon, an alternate timeline from Dark Horse Comics pitted them together with a rather unexpected ending. Similar to Marvel's What If...? stories, the non-canon Star Wars Infinities consisted of three miniseries featuring a major change for each episode of the original trilogy of films. As such, the alternate narrative for The Empire Strikes Back saw Darth Vader facing Yoda on the swamp planet of Dagobah.
In 2002's four-part Star Wars Infinities: The Empire Strikes Back from Dave Land and Davidé Fabbai, Luke Skywalker is killed on Hoth. Rather than escaping the wampa cave and being rescued by Han Solo, Luke is instead mauled by the brutal creatures. Surviving just long enough to tell Han about his vision to travel to Dagobah to learn from Yoda and become a Jedi, Luke dies from his wounds with his destiny going to another. While Han initially thinks that he is the one to become a Jedi, the crew of the Millennium Falcon travel to Dagobah and discover that Leia is to learn the ways of the Force from Yoda instead of her brother. However, Darth Vader and the Empire are hot on their trail following the Battle of Hoth.
In Star Wars Infinities: The Empire Strikes Back #4, Darth Vader learns that Yoda and the child of Anakin Skywalker are on Dagobah. Facing Grand Master Yoda, Vader's mind is entered by the diminutive yet powerful Jedi, who summons various Force ghosts of Obi-Wan Kenobi, Qui-Gon Jinn, and Mace Windu to attack the Dark Lord of the Sith within his own mindscape. This reduces Vader to nothing more than the boy he once was. However, the pain of learning that his son is dead gives Vader the rage and power he needs to overcome Yoda's hold, freeing himself and cutting off the Jedi Master's arm. It is then that Leia runs in to face Vader by herself.
While the end of the issue ultimately sees Leia and Han defeating Vader and restoring balance to the universe, Vader's defeat of Yoda is rather impressive. It certainly serves as a potential indication of what might have happened if Vader and Yoda had ever fought in the main Star Wars timeline, rather than taking place in a series that wasn't canon even before Disney's purge when the company purchased Lucasfilm back in 2012.
While Yoda's age likely plays a factor, the issue largely affirms that the rage and pain of Darth Vader is a force to be reckoned with regardless of the timeline. Infinities was a great miniseries that wondered what would happen if things had gone differently in the Star Wars universe. As such, Darth Vader's surprising defeat of Yoda serves to be one of the series' most exciting changes taking place in an alternate Star Wars timeline.