Derek Fisher has lost the most career games in the playoffs, with 98 losses.

most playoff losses by a player in their career
FisherMaloneDuncanStocktonJamesParkerHorryO'NealBryantGinobiliPierceAbdul-JabbarKiddWallacePerkinsAingeRobinsonParishNowitzkiOakleyJohnsonKorverPaytonGarnettSilas98959493928989878583838379797978777776767574747373
NAMEGPLMPGPPGRPGAPGSPGBPGTPGFGMFGAFG%3PM3PA3P%FTMFTAFT%MINPTSREBASTSTLBLKTOVPF+/-
Derek FisherDerek Fisher2599826.58.32.22.31.10.10.92.86.742.21.12.839.91.51.980.56,8562,14657859827216237645+725
Karl MaloneKarl Malone1939541.024.710.73.21.30.72.89.019.546.30.00.216.26.68.973.67,9074,7612,062610258135550662+123
Tim DuncanTim Duncan2519437.320.611.43.00.72.32.57.915.750.10.00.114.34.87.068.99,3705,1722,859764168568633701+1090
John StocktonJohn Stockton1829335.213.43.310.11.90.32.84.79.947.30.61.932.63.44.281.06,3982,4366081,83933850517539+105
LeBron JamesLeBron James2669241.528.79.07.21.70.93.710.220.749.51.64.833.76.68.974.011,0357,6312,3911,919454252975616+1310
Tony ParkerTony Parker2268934.317.92.95.10.90.12.67.115.546.10.51.730.93.14.273.17,7584,0456661,14319819594429+581
Robert HorryRobert Horry2448928.07.95.62.41.10.91.22.76.442.61.13.035.91.42.072.26,8231,9391,361575276225282717+590
Shaquille O'NealShaquille O'Neal2168737.524.311.62.70.52.13.09.416.856.30.00.05.410.750.48,0985,2502,508582117459649769+638
Kobe BryantKobe Bryant2208539.325.65.14.71.40.72.99.220.544.81.34.033.16.07.481.68,6415,6401,1191,040310144647660+555
Manu GinobiliManu Ginobili2188327.914.04.03.81.30.32.24.410.143.31.54.235.83.84.681.76,0753,05487482729261481588+951
Paul PiercePaul Pierce1708336.618.75.83.41.20.62.86.014.242.31.64.635.55.16.183.06,2293,180985579204105476547+160
Kareem Abdul-JabbarKareem Abdul-Jabbar2378337.324.310.53.21.02.42.69.918.753.30.00.00.04.46.074.08,8515,7622,481767189476447797
Jason KiddJason Kidd1587938.512.96.78.01.90.32.84.611.739.11.54.632.22.33.078.16,0882,0431,0581,26330252450348+110
Rasheed WallaceRasheed Wallace1777933.013.56.21.50.81.31.35.211.744.41.13.135.22.02.871.75,8382,3841,099264145225228645+325
Sam PerkinsSam Perkins1677928.711.15.61.50.70.81.23.98.944.40.92.536.32.43.078.54,7851,861936246118126207441+14
Danny AingeDanny Ainge1937826.19.92.33.40.90.11.33.78.145.60.92.239.71.51.882.95,0381,90244365617219257533
Clifford RobinsonClifford Robinson1417727.610.33.91.81.00.91.63.89.739.30.62.129.82.03.262.93,8871,453554250141132230496-136
Robert ParishRobert Parish1847733.615.39.61.30.81.72.16.212.250.60.00.00.03.04.272.26,1772,8201,765234145309365617-3
Dirk NowitzkiDirk Nowitzki1457640.725.310.02.51.00.92.38.418.246.21.02.836.57.48.389.25,8953,6631,446360149129328407+48
Charles OakleyCharles Oakley1447635.510.810.02.01.20.32.14.18.845.90.10.336.62.53.475.55,1081,5501,44528317842308503-60
Dennis JohnsonDennis Johnson1807538.917.34.35.61.40.62.76.514.843.90.20.823.64.25.280.26,9943,1167811,006247113480575
Kyle KorverKyle Korver1457423.28.02.51.00.60.40.82.76.441.71.84.539.10.91.089.53,3701,1563601528156119282+257
Gary PaytonGary Payton1547435.614.03.75.31.40.21.95.612.644.10.92.831.52.02.870.65,4812,15557581121632297434-15
Kevin GarnettKevin Garnett1437336.918.210.73.31.21.32.47.415.547.80.10.427.33.34.178.95,2832,6011,534471178186342431+298
Paul SilasPaul Silas1637328.36.99.42.10.80.31.42.46.139.70.00.02.02.969.24,6191,1241,527335813473469