The fourth Bucky in the Marvel Comics chronology was Rikki Barnes.
The granddaughter of James Buchanon Barnes (who, this time, didn't die as Cap's former partner "Bucky") and Peggy Carter in the alternate universe known as the Franklinverse, she fought alongside Captain America, the Falcon and Nicholas Fury against the "World Party" a pro-Nazi organisation run by the universe's version of theRed Skull and Master Man.
After Captain America left the Franklinverse with the other heroes, Doctor Doom took over as its supreme ruler. As Bucky, Rikki Barnes led a team of vigilantes, who began calling themselves the Young Allies.
The team consisted of Bucky, the man-bull Toro, Kymellian hybrid Kid Colt and telepath extraordinaire IQ.
Bucky and Toro even found their way to Latveria in the real Marvel Universe where they were posing as eco-terrorists to protest Doom's rule over their planet. (as seen in Thunderbolts issue #52)
Many were apprehensive about the idea of a female Bucky, but I personally thought she added a new depth to the tradition of the Star-Spangled Avenger's sidekick. Plus, it also showed that girls digged comics too!
Okay, I should stop being delusional.