Josh Smith has blocked the most career shots by a player younger than 21, with 381 blocks.

Interpreted as:

most blocks before turning 21 years old by a player

	NAME	BLK	GP	MPG	PPG	RPG	APG	SPG	BPG	FGM	FGA	FG%	3PM	3PA	3P%	FTM	FTA	FT%	TS%	OREB	DREB	TPG	MIN	PTS	REB	AST	STL	TOV	PF	+/-
1	Josh Smith J. Smith	381	169	30.5	10.6	6.6	2.1	0.8	2.3	3.9	9.1	43.2	0.3	1.1	27.1	2.5	3.5	70.3	49.8	2.1	4.5	2.0	5,159	1,799	1,110	363	142	338	467	-697
2	Victor Wembanyama V. Wembanyama	366	100	30.6	22.7	10.5	3.9	1.2	3.7	8.2	17.4	47.2	2.3	6.6	34.0	4.0	5.0	81.6	58.0	2.2	8.4	3.6	3,060	2,273	1,053	386	118	363	215	-10
3	Kevin Garnett K. Garnett	294	157	33.7	13.7	7.1	2.4	1.2	1.9	5.8	11.7	49.6	0.1	0.3	28.6	2.0	2.7	73.6	53.1	2.3	4.8	1.8	5,288	2,144	1,119	381	191	285	388	+116
4	Dwight Howard D. Howard	292	184	34.9	14.2	11.5	1.3	0.8	1.6	5.1	9.5	53.5	0.0	0.0	0.0	4.0	6.4	62.9	57.6	3.5	7.9	2.4	6,415	2,619	2,109	233	152	449	562	-106
5	Tracy McGrady T. McGrady	278	192	24.7	11.1	5.5	2.5	1.0	1.4	4.2	9.4	44.8	0.2	0.7	28.4	2.4	3.4	71.2	50.7	2.2	3.3	1.6	4,747	2,122	1,048	474	191	306	381	-262
6	Anthony Davis A. Davis	272	119	31.9	16.8	9.1	1.2	1.3	2.3	6.5	12.6	51.9	0.0	0.1	15.4	3.7	4.9	76.2	57.0	2.9	6.2	1.5	3,802	2,001	1,084	148	153	184	330	-242
7	Bismack Biyombo B. Biyombo	258	143	25.5	5.0	6.6	0.4	0.3	1.8	2.0	4.4	45.7	0.0	0.0		1.0	2.0	50.2	47.6	2.1	4.5	1.1	3,641	713	950	62	48	153	340	-833
8	Eddie Griffin E. Griffin	245	150	25.2	8.7	5.8	0.9	0.5	1.6	3.4	9.0	38.3	1.0	3.1	33.1	0.8	1.2	67.8	45.9	1.7	4.1	0.8	3,786	1,306	877	139	69	123	253	-10
9	Myles Turner M. Turner	232	130	27.2	12.6	6.4	1.0	0.7	1.8	5.0	9.9	50.4	0.3	0.9	32.8	2.3	3.0	77.7	56.2	1.4	5.0	1.2	3,534	1,638	833	132	90	159	388	+27
10	Darius Miles D. Miles	228	163	26.7	9.4	5.7	1.7	0.7	1.4	3.8	7.8	49.3	0.0	0.2	10.5	1.7	3.0	57.2	51.7	1.4	4.3	1.9	4,360	1,540	930	283	122	307	375	+36
11	Andre Drummond A. Drummond	226	141	27.4	11.1	10.8	0.5	1.1	1.6	4.9	7.9	61.8	0.0	0.0	25.0	1.4	3.5	40.2	59.3	4.3	6.5	1.2	3,862	1,571	1,528	65	160	167	417	-284
12	Andrew Bynum A. Bynum	222	163	19.3	7.2	5.6	1.0	0.2	1.4	2.9	5.0	57.1	0.0	0.0	0.0	1.4	2.2	64.9	59.7	1.7	3.9	1.1	3,140	1,171	920	164	28	184	403	+80
13	Shaquille O'Neal S. O'Neal	212	54	38.1	24.0	14.2	1.6	0.8	3.9	9.3	16.2	57.3	0.0	0.0	0.0	5.4	9.3	58.8	59.2	4.5	9.6	4.0	2,055	1,294	765	88	41	215	216
14	Jarrett Allen J. Allen	208	152	23.3	9.6	7.0	1.0	0.5	1.4	3.7	6.3	59.0	0.1	0.4	18.3	2.0	2.8	73.2	63.4	2.2	4.8	1.2	3,537	1,460	1,060	159	71	185	331	-264
15	Andris Biedrins A. Biedrins	199	172	21.0	6.5	6.5	0.7	0.6	1.2	2.9	4.8	60.8	0.0	0.0	0.0	0.7	1.6	46.0	59.7	2.4	4.1	0.9	3,606	1,122	1,122	120	97	159	551	+131
16	Tyson Chandler T. Chandler	199	146	22.0	7.7	5.9	0.9	0.4	1.4	2.8	5.4	51.8	0.0	0.0		2.1	3.5	60.6	55.6	1.9	3.9	1.6	3,216	1,127	857	130	65	234	399	-513
17	Chris Bosh C. Bosh	194	141	34.8	13.7	8.0	1.4	0.9	1.4	5.0	10.6	46.5	0.0	0.1	33.3	3.7	5.2	72.2	53.0	2.5	5.5	1.8	4,901	1,930	1,124	203	122	254	401	-140
18	Jaren Jackson Jr. J. Jackson Jr.	174	115	27.3	15.5	4.6	1.2	0.8	1.5	5.7	11.7	48.5	1.7	4.4	38.4	2.5	3.3	75.7	59.2	1.1	3.5	1.7	3,137	1,788	534	142	92	197	452	-207
19	Giannis Antetokounmpo G. Antetokounmpo	169	178	28.6	10.5	5.7	2.3	0.8	0.9	3.8	8.1	47.1	0.3	1.1	29.7	2.6	3.6	73.7	54.7	1.1	4.5	1.9	5,095	1,874	1,006	410	151	342	502	-254
20	Isaiah Stewart I. Stewart	164	139	23.5	8.1	7.7	1.0	0.4	1.2	3.4	6.5	52.9	0.3	0.8	33.0	1.0	1.4	70.8	57.2	2.8	4.9	1.1	3,270	1,126	1,070	141	61	152	395	-427
21	Karl-Anthony Towns K. Towns	149	91	32.3	18.7	10.3	2.0	0.7	1.6	7.7	14.3	53.7	0.5	1.3	35.8	2.8	3.5	80.3	58.9	2.8	7.5	2.2	2,943	1,702	939	185	66	202	275	-127
22	Mitchell Robinson M. Robinson	147	60	19.5	7.0	6.1	0.5	0.8	2.5	2.9	4.3	68.6	0.0	0.0		1.1	1.9	57.8	68.1	2.7	3.4	0.5	1,170	417	365	32	47	31	195	-163
23	Nerlens Noel N. Noel	142	75	30.8	9.9	8.1	1.7	1.8	1.9	4.0	8.7	46.2	0.0	0.0		1.9	3.1	60.9	49.3	2.5	5.7	1.9	2,311	744	611	128	133	146	208	-430
24	Marquese Chriss M. Chriss	140	154	21.2	8.5	4.8	0.9	0.8	0.9	3.2	7.2	43.8	0.8	2.7	30.9	1.4	2.2	61.7	52.0	1.1	3.7	1.4	3,270	1,309	743	143	118	215	468	-677
25	Alperen Şengün A. Şengün	138	147	24.9	12.3	7.3	3.2	0.9	0.9	4.7	9.0	52.2	0.3	1.2	27.6	2.5	3.5	71.3	58.0	2.6	4.7	2.3	3,660	1,801	1,071	476	129	338	472	-592