Jayson Tatum has the highest career plus/minus by a player younger than 26, at +2992.

nba career plus minus leader before 26 years-old

NAME	+/-	GP	MPG	PPG	RPG	APG	SPG	BPG	TPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	MIN	PTS	REB	AST	STL	BLK	TOV	PF
Jayson Tatum	+2992	495	34.2	23.0	7.2	3.5	1.1	0.7	2.3	8.0	17.4	46.1	2.5	6.7	37.4	4.4	5.3	84.4	16,926	11,381	3,546	1,719	545	336	1,134	1,043
Tony Parker	+2899	540	33.1	16.0	3.1	5.5	1.0	0.1	2.5	6.3	13.0	48.7	0.5	1.7	31.4	2.8	3.9	71.6	17,879	8,638	1,680	2,959	539	40	1,347	1,046
LeBron James	+2601	582	40.2	27.6	7.0	7.0	1.7	0.9	3.3	9.8	20.6	47.5	1.4	4.2	33.1	6.7	8.9	74.4	23,378	16,081	4,089	4,057	1,003	496	1,929	1,144
Tim Duncan	+2530	370	39.3	22.8	12.2	3.1	0.8	2.4	3.2	8.7	17.1	50.9	0.0	0.2	15.4	5.4	7.6	71.1	14,545	8,440	4,505	1,131	297	892	1,172	1,075
Kawhi Leonard	+2391	398	30.5	16.4	6.2	2.3	1.8	0.7	1.4	6.0	12.1	49.5	1.3	3.4	38.8	3.1	3.7	84.7	12,154	6,508	2,469	903	705	280	542	697
Kobe Bryant	+2329	561	34.4	21.8	5.0	4.3	1.5	0.6	2.7	7.7	16.9	45.4	0.9	2.6	33.1	5.5	6.6	83.4	19,273	12,215	2,817	2,390	826	348	1,510	1,499
Dirk Nowitzki	+2202	444	35.9	20.4	8.3	2.4	1.0	1.0	1.8	7.1	15.2	46.4	1.5	4.0	37.2	4.8	5.6	85.3	15,944	9,074	3,664	1,055	457	459	802	1,250
Dwight Howard	+2093	567	36.0	18.2	12.9	1.5	1.0	2.2	3.1	6.4	11.0	57.8	0.0	0.0	3.8	5.4	9.1	59.8	20,401	10,322	7,287	831	545	1,228	1,755	1,843
Rajon Rondo	+1943	406	32.2	10.9	4.4	7.7	1.9	0.1	2.6	4.5	9.3	48.6	0.1	0.6	24.3	1.8	2.8	62.2	13,081	4,424	1,794	3,113	784	54	1,055	925
Klay Thompson	+1895	354	32.3	18.0	3.2	2.3	0.9	0.6	1.8	6.7	14.9	44.8	2.7	6.3	42.0	2.0	2.4	84.6	11,438	6,368	1,145	827	318	196	636	844
Draymond Green	+1703	299	24.7	8.3	6.3	3.1	1.2	0.9	1.5	3.0	7.0	43.2	0.8	2.5	33.9	1.4	2.1	67.9	7,381	2,472	1,888	933	353	268	456	822
James Harden	+1702	452	32.3	19.7	4.3	4.4	1.4	0.4	2.7	5.8	13.1	44.4	2.0	5.3	37.0	6.1	7.2	85.4	14,616	8,886	1,933	2,008	645	186	1,230	1,120
Blake Griffin	+1493	360	35.6	21.5	9.8	3.9	1.0	0.6	2.5	8.3	15.9	52.4	0.1	0.4	25.6	4.7	7.2	65.2	12,806	7,743	3,521	1,400	355	216	900	1,120
Steven Adams	+1484	467	26.8	9.7	7.4	1.0	0.9	1.0	1.4	4.0	6.8	58.8	0.0	0.0	0.0	1.6	2.9	55.3	12,528	4,507	3,446	469	418	464	663	1,262
Nikola Jokic	+1475	409	29.5	17.7	9.7	5.7	1.1	0.7	2.6	6.8	12.9	52.9	1.0	2.8	34.4	3.1	3.8	83.0	12,052	7,228	3,969	2,338	467	283	1,055	1,170
Serge Ibaka	+1406	446	28.2	11.4	7.5	0.5	0.4	2.6	1.3	4.8	9.0	53.3	0.3	0.7	37.2	1.5	2.0	74.4	12,599	5,071	3,342	243	186	1,152	563	1,280
Donovan Mitchell	+1404	345	33.7	23.9	4.2	4.5	1.3	0.3	2.8	8.6	19.4	44.1	2.8	7.7	36.1	4.0	4.8	83.3	11,637	8,234	1,433	1,542	445	99	964	874
Amar'e Stoudemire	+1397	391	34.0	21.0	9.0	1.3	0.9	1.5	2.5	7.5	13.9	54.2	0.0	0.2	16.2	5.9	7.9	74.8	13,281	8,225	3,532	514	357	594	991	1,359
Rasheed Wallace	+1381	269	33.6	14.9	6.3	1.8	1.0	1.1	1.9	6.1	11.4	53.0	0.1	0.6	24.8	2.7	3.9	68.1	9,047	4,015	1,704	471	258	308	518	857
Peja Stojakovic	+1363	340	31.7	16.7	4.8	1.9	1.0	0.1	1.6	6.1	13.1	46.5	1.7	4.5	38.5	2.9	3.3	86.9	10,778	5,694	1,623	658	337	46	528	547
Russell Westbrook	+1338	442	33.9	20.1	4.9	6.9	1.6	0.3	3.5	7.1	16.4	43.3	0.7	2.4	30.5	5.1	6.3	81.6	14,973	8,874	2,174	3,055	722	132	1,552	1,047
Jamal Murray	+1334	390	30.4	16.8	3.7	4.1	1.0	0.3	2.0	6.2	13.8	44.8	2.0	5.4	37.1	2.5	2.8	87.1	11,851	6,549	1,444	1,583	371	118	772	707
Michael Porter Jr.	+1327	268	27.8	15.7	6.2	1.2	0.6	0.6	1.1	6.0	11.9	49.9	2.4	5.9	41.0	1.3	1.7	80.7	7,443	4,199	1,669	320	156	163	298	509
Tayshaun Prince	+1277	262	31.3	11.3	4.3	2.2	0.6	0.7	1.3	4.4	9.5	46.5	0.7	1.8	36.3	1.8	2.3	78.2	8,201	2,962	1,117	582	167	177	338	407
Kevin Garnett	+1227	449	39.2	20.4	10.6	4.5	1.4	1.8	2.7	8.3	17.1	48.3	0.2	0.7	31.5	3.6	4.7	76.1	17,617	9,159	4,751	2,010	649	793	1,229	1,168