Shaquille O'Neal has gotten the most career offensive rebounds in the playoffs, with 866 rebounds.

most playoff offensive rebounds
Interpreted as:
most playoff offensive rebounds by a player
O'NealDuncanRodmanParishGrantOakleyBarkleyMaloneAbdul-JabbarMaloneOlajuwonPippenWallaceMcHaleHowardHorryJamesGreenDavisGasolRobinsonBirdErvingDrexlerWilliams866778626571549519510510505502471466463456441410401390389373367360360359351
NAMEGPOREBMPGPPGRPGAPGSPGBPGTPGFGMFGAFG%3PM3PA3P%FTMFTAFT%MINPTSREBASTSTLBLKTOVPF+/-
Shaquille O'NealShaquille O'Neal21686637.524.311.62.70.52.13.09.416.856.30.00.05.410.750.48,0985,2502,508582117459649769+638
Tim DuncanTim Duncan25177837.320.611.43.00.72.32.57.915.750.10.00.114.34.87.068.99,3705,1722,859764168568633701+1090
Dennis RodmanDennis Rodman16962628.36.49.91.20.60.61.52.65.349.00.00.314.91.12.154.04,7891,0811,67620510697258630+127
Robert ParishRobert Parish18457133.615.39.61.30.81.72.16.212.250.60.00.00.03.04.272.26,1772,8201,765234145309365617-3
Horace GrantHorace Grant17054936.311.28.62.11.01.01.14.68.753.00.00.012.52.02.871.46,1721,9071,457360171173184515+61
Charles OakleyCharles Oakley14451935.510.810.02.01.20.32.14.18.845.90.10.336.62.53.475.55,1081,5501,44528317842308503-60
Charles BarkleyCharles Barkley12351039.423.012.93.91.60.92.98.216.051.30.52.025.56.18.571.74,8492,8331,582482193108353408+1
Moses MaloneMoses Malone9451040.422.113.81.40.91.62.68.016.747.90.00.114.36.18.076.23,7962,0771,29513684151215244
Kareem Abdul-JabbarKareem Abdul-Jabbar19650536.023.49.13.21.02.42.69.517.554.50.00.00.04.35.875.47,0534,5851,778618189476447666
Karl MaloneKarl Malone19350241.024.710.73.21.30.72.89.019.546.30.00.216.26.68.973.67,9074,7612,062610258135550662+123
Hakeem OlajuwonHakeem Olajuwon14547139.625.911.23.21.73.32.910.419.652.80.00.122.25.17.171.95,7493,7551,621458245472424562-29
Scottie PippenScottie Pippen20846639.017.57.65.01.90.92.96.414.544.41.03.230.33.75.172.48,1053,6421,5831,048395185602686+232
Ben WallaceBen Wallace13046334.87.211.21.31.51.91.02.85.848.20.00.10.01.63.941.84,5249391,454173199250136296+368
Kevin McHaleKevin McHale16945633.818.87.41.60.41.71.97.112.756.10.00.138.14.55.878.85,7163,1821,25327465281326571
Dwight HowardDwight Howard12544131.615.311.81.20.82.02.65.49.258.90.00.114.34.48.054.83,9451,9091,47314994248323467-77
Robert HorryRobert Horry24441028.07.95.62.41.10.91.22.76.442.61.13.035.91.42.072.26,8231,9391,361575276225282717+590
LeBron JamesLeBron James26640141.528.79.07.21.70.93.710.220.749.51.64.833.76.68.974.011,0357,6312,3911,919454252975616+1310
A.C. GreenA.C. Green15339026.98.67.10.80.70.31.03.06.347.50.10.325.02.63.573.94,1191,3151,08413010046146340-44
Dale DavisDale Davis13738926.76.68.00.60.60.91.12.75.053.30.00.00.01.22.450.33,6629001,0918779126153408-15
Pau GasolPau Gasol13637335.515.49.23.20.51.71.86.011.850.80.10.329.73.44.674.14,8252,0981,24643871233250356+225
David RobinsonDavid Robinson12336734.318.110.62.31.22.52.36.213.047.90.00.110.05.67.970.84,2212,2211,301280151312280423+362
Larry BirdLarry Bird16436042.023.810.36.51.80.93.18.918.847.20.51.532.15.56.289.06,8863,8971,6831,062296145506466
Julius ErvingJulius Erving14136037.521.97.04.21.71.73.28.417.348.60.10.319.45.06.477.95,2883,088994594235239396403
Clyde DrexlerClyde Drexler14535938.420.46.96.11.90.72.77.416.644.71.03.428.84.65.978.75,5722,9631,002891278108397486+52
Buck WilliamsBuck Williams10835134.411.28.71.00.80.61.84.07.852.00.00.050.03.14.767.23,7101,2119411139070190386+2
StatMuse has season-level data for offensive rebounds going back to the 1974 playoffs.