Dwight Howard has gotten the most career rebounds by a player younger than 20, with 1,061 rebounds.

Interpreted as:

most rebounds before turning 20 years old by a player

	NAME	REB	GP	MPG	PPG	RPG	APG	SPG	BPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	TS%	OREB	DREB	TPG	MIN	PTS	AST	STL	BLK	TOV	PF	+/-
1	Dwight Howard D. Howard	1,061	100	33.3	12.4	10.6	1.0	0.9	1.6	4.5	8.8	51.1	0.0	0.0	0.0	3.5	5.3	65.2	55.9	3.5	7.1	2.0	3,327	1,243	100	94	163	203	297	-216
2	Jalen Duren J. Duren	680	75	25.3	9.5	9.1	1.3	0.7	0.9	4.1	6.3	64.4	0.0	0.0	0.0	1.4	2.3	62.1	65.3	3.4	5.6	1.5	1,901	713	100	49	68	114	210	-321
3	LeBron James L. James	634	108	39.9	21.9	5.9	6.2	1.9	0.8	8.2	18.8	43.5	0.8	2.7	30.8	4.6	6.1	75.6	50.8	1.3	4.6	3.4	4,307	2,362	673	202	83	367	202	-11
4	Jabari Smith Jr. J. Smith Jr.	569	79	31.0	12.8	7.2	1.3	0.5	0.9	4.6	11.3	40.8	1.5	4.9	30.7	2.1	2.6	78.6	51.4	1.5	5.7	1.3	2,450	1,010	101	43	74	104	227	-555
5	Andrew Bynum A. Bynum	564	128	16.7	5.6	4.4	0.8	0.1	1.2	2.2	4.1	53.3	0.0	0.0	0.0	1.2	1.9	62.7	56.3	1.4	3.1	1.0	2,132	711	103	16	150	132	305	-159
6	Tracy McGrady T. McGrady	547	113	20.2	8.0	4.8	1.9	0.9	1.1	3.1	6.9	44.3	0.2	0.7	28.9	1.7	2.4	72.0	50.4	2.0	2.8	1.3	2,285	909	211	101	127	146	180	-258
7	Josh Smith J. Smith	531	90	27.2	9.5	5.9	1.6	0.8	2.0	3.6	8.2	44.1	0.0	0.3	14.8	2.2	3.2	69.8	49.5	1.9	4.0	1.8	2,447	851	143	71	176	164	198	-466
8	Kevin Garnett K. Garnett	501	80	28.7	10.4	6.3	1.8	1.1	1.6	4.5	9.2	49.1	0.1	0.4	28.6	1.3	1.9	70.5	52.2	2.2	4.1	1.4	2,293	835	145	86	131	110	189
9	Carmelo Anthony C. Anthony	498	82	36.5	21.0	6.1	2.8	1.2	0.5	7.6	17.9	42.6	0.8	2.6	32.2	5.0	6.4	77.7	50.9	2.2	3.8	3.0	2,995	1,725	227	97	41	247	225	+65
10	Darius Miles D. Miles	477	81	26.3	9.4	5.9	1.2	0.6	1.5	3.9	7.8	50.5	0.0	0.2	5.3	1.5	2.9	52.1	51.8	1.6	4.3	1.8	2,133	761	99	51	125	147	191	+30
11	Giannis Antetokounmpo G. Antetokounmpo	463	98	25.1	7.9	4.7	2.0	0.7	0.7	2.7	6.2	43.3	0.4	1.3	32.8	2.0	2.9	69.6	52.3	1.1	3.7	1.6	2,460	770	194	73	73	156	225	-183
12	Chris Bosh C. Bosh	461	63	32.9	11.2	7.3	1.0	0.7	1.4	4.2	9.3	45.7	0.0	0.1	37.5	2.7	3.9	68.4	50.9	2.6	4.7	1.4	2,074	704	65	46	86	86	176	-139
13	Andre Drummond A. Drummond	457	60	20.7	7.9	7.6	0.5	1.0	1.6	3.5	5.7	60.8	0.0	0.0	50.0	1.0	2.7	37.1	57.8	2.8	4.8	1.0	1,243	476	30	59	95	57	144	-51
14	Michael Kidd-Gilchrist M. Kidd-Gilchrist	455	78	26.0	9.0	5.8	1.5	0.7	0.9	3.6	7.9	45.8	0.0	0.1	22.2	1.8	2.4	74.9	50.6	1.7	4.2	1.3	2,025	704	117	54	70	101	164	-286
15	Isaiah Stewart I. Stewart	453	68	21.4	7.9	6.7	0.9	0.6	1.3	3.3	6.0	55.3	0.3	0.9	33.3	0.9	1.4	69.6	59.7	2.3	4.3	1.0	1,455	537	59	39	86	67	184	-60
16	Alex Sarr A. Sarr	435	67	27.1	13.0	6.5	2.4	0.7	1.5	4.9	12.4	39.4	1.6	5.1	30.8	1.7	2.5	67.9	48.2	1.9	4.6	1.7	1,814	869	161	44	101	114	146	-547
17	Josh Giddey J. Giddey	421	54	31.5	12.5	7.8	6.4	0.9	0.4	5.2	12.4	41.9	1.0	3.9	26.3	1.0	1.5	70.9	47.8	1.8	6.0	3.2	1,700	674	345	51	20	171	88	-299
18	Eddie Griffin E. Griffin	416	73	26.0	8.8	5.7	0.7	0.2	1.8	3.3	9.1	36.6	1.2	3.7	33.0	0.9	1.2	74.4	45.6	1.6	4.1	0.6	1,896	642	53	17	134	47	117	-161
19	Luka Dončić L. Dončić	415	57	32.2	20.9	7.3	5.7	1.0	0.3	6.9	15.9	43.4	2.5	7.0	35.3	4.7	6.5	72.6	56.0	1.1	6.2	3.4	1,837	1,194	324	57	16	194	107	-16
20	Derrick Favors D. Favors	412	78	19.7	6.8	5.3	0.5	0.4	0.9	2.8	5.3	51.7	0.0	0.0		1.3	2.2	59.5	54.2	2.2	3.1	1.0	1,536	533	39	29	68	77	246	-233
21	Alperen Sengun A. Sengun	393	72	20.7	9.6	5.5	2.6	0.8	0.9	3.5	7.3	47.4	0.4	1.6	24.8	2.3	3.2	71.1	55.2	1.9	3.5	2.0	1,489	692	185	59	68	145	214	-309
22	Jarrett Allen J. Allen	388	72	20.0	8.2	5.4	0.7	0.4	1.2	3.3	5.5	58.9	0.1	0.2	33.3	1.6	2.0	77.6	63.6	2.0	3.4	1.1	1,441	587	49	28	88	82	147	-145
23	Anthony Davis A. Davis	384	49	28.0	12.9	7.8	0.9	1.1	1.8	5.2	10.3	50.8	0.0	0.1	0.0	2.4	3.3	72.5	54.6	2.4	5.4	1.4	1,372	630	45	54	87	69	112	-108
24	Marvin Williams M. Williams	383	79	24.7	8.5	4.8	0.8	0.6	0.3	3.0	6.7	44.3	0.2	0.7	24.5	2.4	3.2	74.7	52.3	1.5	3.3	1.1	1,952	672	63	48	24	83	227	-87
25	Kobe Bryant K. Bryant	374	150	21.1	11.7	2.5	1.9	0.8	0.4	3.8	8.9	42.5	0.8	2.4	35.4	3.3	4.2	80.1	54.7	0.8	1.7	1.8	3,159	1,759	290	123	63	269	282	+324