Kobe.
After the 2004 NBA Finals he was a free-agent and made it known he wanted the team to himself. So the Lakers traded Shaq to Miami, the coach Phil Jackson walked out because Kobe "un-coachable", Gary Payton wasn't re-signed and Karl Malone didn't initially re-sign (Malone & Payton were considered Shaq guys, Payton confronted Kobe in practice that season about his selfishness).
Malone entered the 2004-05 season still a free-agent and around mid-season was considering re-signing with the Lakers then a story was leaked that Malone either hit on Kobe's wife or liked her or something and when that blew up in the media he quietly slipped into retirement instead. No points for guessing where that leak probably came from.
I followed all this pretty closely and to this day I still consider Kobe's performance in the 2004 NBA Finals to be disgraceful in that I think he intentionally threw that series because if they had have won everyone would've called for Phil, Malone & Payton to come back the next season and try and go back-to-back.
Kobe did more than shoot the team out of that series. He intentionally ignored Shaq rarely throwing the ball into him and kept shooting over double teams and sometimes even triple teams. Once the Pistons realised what was going on they didn't even bother doubling Shaq and just left the comparatively tiny Ben Wallace on him straight up. It was pretty painful to watch those last 3 games in Detroit and it didn't help Malone getting injured about halfway through the series and taking no further part either.
Keep in mind after Phil Jackson quit the Lakers hired Rudy Tomjanovich as their new coach. He signed some big 4 or 5 year deal. In his playing days Rudy T was an alcoholic but had kicked it by the time he became a coach and led Houston to those back-to-back titles in the mid-90's.
The 2004-05 season Kobe went nuts with the jacking up everything no longer having Phil, Shaq etc to reign him in and Rudy T only lasted half a season before quitting reportedly turning back to the bottle.
Yes Phil came back the following season when the Lakers desperate after watching Kobe chuck them out of that season not even coming close to making the playoffs but Phil had all the leverage and asked for a cool $12 million a year.
The excuse Kobe used to use for getting Shaq traded was because he didn't like Shaq's work ethic. The reality was he wanted the spotlight to himself and was jealous of Shaq winning those three Finals MVP's when the Lakers won those three championsips in a row from 2000-2002.