Beckham and Donovan are now retired, leaving Keane as the Galaxy's preeminent player. But it's a stature Keane earned this year after the forward's stellar 2014 season.
Keane, 34, was named Major League Soccer's most valuable player Dec. 3, then scored the winning goal in the Galaxy's 2-1 MLS Cup victory over the New England Revolution last Sunday to give the Galaxy a record fifth championship.
The Galaxy won three of those titles in the last four years, all after Keane joined the club.
"Robbie has been unbelievable since he stepped foot in MLS," Galaxy Coach Bruce Arena said after Sunday's game.
After being limited to 23 games last year, Keane had off-season surgeries on his Achilles' tendons and then stormed back with a team-high 19 goals in the regular season, third-highest in the MLS and up from his 16 goals in 2012 and 2013.
In the 29 games in which Keane played this year, the Galaxy was 15-5-9.
"I want people to know that I've been a good scorer, a good leader and a player that tried to help the team win a championship," Keane said via email Wednesday. "That's it, really."
The Galaxy captain also had 14 assists, second on the team behind the 19 recorded by Donovan, the MLS' career leader in scoring and assists who retired after the championship game Sunday.
"The most important thing to me is to be consistent," Keane said. "Every year I've just gotten better and better."
Although Keane has another year left on his contract, he hinted after the MLS Cup game that he was mulling whether to leave the Galaxy.
"I definitely need to recharge the batteries and see what the next chapter is for me, whether it's here or it's somewhere else," he told reporters. "Sometimes change is good for everybody."
But Arena said, "I'm anticipating he's returning to the Galaxy."
Beckham, who retired from the Galaxy after the 2012 season, began recruiting Keane to the Galaxy in early 2011 while Beckham was training with Tottenham Hotspur of the English Premier League.
Keane twice played for Tottenham as part of an accomplished Premier League career, and his European play also included a stint on loan with Celtic of the Scottish Premier League, where he scored 16 goals in 19 games in 2010.
When he signed with the Galaxy at age 31, there were whispers Keane did so because his best playing days, at least in Europe, were behind him. Keane rejected that notion, saying he wanted to play with the Galaxy for the new challenge it presented.
"It was just time for a new chapter in my career," Keane said at the time.
And after joining the Galaxy, Keane continued as the captain for the Irish national team, where the Dublin native holds the records for scoring (65 goals) and appearances (138 caps). His play with Ireland this year was the main reason Keane did not play the full 34-game season for the Galaxy.
Keane on the field is an intense, tempestuous forward who constantly gesticulates with his arms to show his ire with referees' foul calls, or lack of them, and at times his displeasure with his teammates' failures and his own.
But he performs gleeful cartwheels after his goals, and Keane's scoring ability reflects not only his mechanical skills and athleticism but his intelligence about finding the optimum spots on the field before he receives the ball, his coach and teammates said.
Asked why Keane is so effective, Arena said: "I think his movement off the ball, his first touch and he has a great sense of where to be around the penalty area" near opponents' goals.
"[Keane's] ability to create chances and wreak havoc on defenses is unlike any other," Donovan said in October when he joined others in declaring that Keane should be the league's MVP. "I would absolutely hate to play against him if I was a defender."
With Donovan retired, Keane — who earned $4.5 million this year — would be the Galaxy's highest-paid player. Whether he returns to the Galaxy or plays elsewhere next year, "For me it's not about the money, I'd play for free," Keane said.
"When I'm done playing [professionally] and I go back to Ireland as a manager or whatever, I'll keep playing in a Sunday league with my mates," he said. "That's just the way I am."