Ken Brett is the youngest relief pitcher in a World Series. He was 18 years old in his rookie season.

	NAME	Age	SEASON	SERIES	TM	G	W	L	W%	GS	ERA	SO	CG	SHO	SV	IP	H	ER	R	HR	BB	HBP	GF	IBB	TBF	WP	K/9	BB/9	K/BB	HR/9	K%	BB%	WHIP	BABIP	RA	H/9
1	Ken Brett K. Brett	18	1967	World Series	BOS	2	0	0		0	0.00	1	0	0	0	1.1	0	0	0	0	1	0	2	0	5	0	6.75	6.75	1.00	0.00	20.0	20.0	0.75	.000	0.00	0.00
2	Don Gullett D. Gullett	19	1970	World Series	CIN	3	0	0		0	1.35	4	0	0	0	6.2	5	1	2	0	4	0	2	0	27	0	5.40	5.40	1.00	0.00	14.8	14.8	1.35	.263	2.70	6.75
3	Don Drysdale D. Drysdale	19	1956	World Series	BKN	1	0	0		0	9.00	1	0	0	0	2.0	2	2	2	1	1	0	1	0	9	0	4.50	4.50	1.00	4.50	11.1	11.1	1.50	.167	9.00	9.00
4	Francisco Rodriguez F. Rodriguez	20	2002	World Series	ANA	4	1	1	.500	0	2.08	13	0	0	0	8.2	6	2	3	1	1	0	1	0	32	1	13.50	1.04	13.00	1.04	40.6	3.1	0.81	.294	3.12	6.23
5	Milt Wilcox M. Wilcox	20	1970	World Series	CIN	2	0	1	.000	0	9.00	2	0	0	0	2.0	3	2	2	0	0	0	0	0	9	0	9.00	0.00		0.00	22.2	0.0	1.50	.429	9.00	13.50
6	Dave Boswell D. Boswell	20	1965	World Series	MIN	1	0	0		0	3.38	3	0	0	0	2.2	3	1	1	0	2	0	0	0	13	0	10.13	6.75	1.50	0.00	23.1	15.4	1.88	.375	3.38	10.13
7	Bill Stafford B. Stafford	20	1960	World Series	NYY	2	0	0		0	1.50	2	0	0	0	6.0	5	1	1	0	1	0	0	0	22	0	3.00	1.50	2.00	0.00	9.1	4.5	1.00	.263	1.50	7.50
8	Juan Pizarro J. Pizarro	20	1957	World Series	MIL	1	0	0		0	10.80	1	0	0	0	1.2	3	2	2	0	2	0	0	0	10	0	5.40	10.80	0.50	0.00	10.0	20.0	3.00	.429	10.80	16.20
9	Fred Hutchinson F. Hutchinson	20	1940	World Series	DET	1	0	0		0	9.00	1	0	0	0	1.0	1	1	1	1	1	0	1	0	5	0	9.00	9.00	1.00	9.00	20.0	20.0	2.00	.000	9.00	9.00
10	Herb Pennock H. Pennock	20	1914	World Series	PHA	1	0	0		0	0.00	3	0	0	0	3.0	2	0	0	0	2	0	1	0	12	0	9.00	6.00	1.50	0.00	25.0	16.7	1.33	.286	0.00	6.00
11	Trey Yesavage T. Yesavage	21	2025	World Series	TOR	1	0	0		0	5.40	0	0	0	0	1.2	1	1	1	1	1	0	0	0	6	0	0.00	5.40	0.00	5.40	0.0	16.7	1.20	.000	5.40	5.40
12	Brusdar Graterol B. Graterol	21	2020	World Series	LAD	3	0	0		0	0.00	0	0	0	0	2.0	2	0	0	0	0	0	0	0	8	0	0.00	0.00		0.00	0.0	0.0	1.00	.250	0.00	9.00
13	Julio Urías J. Urías	21	2018	World Series	LAD	3	0	0		0	3.00	2	0	0	0	3.0	1	1	1	0	1	0	0	0	11	0	6.00	3.00	2.00	0.00	18.2	9.1	0.67	.125	3.00	3.00
14	Brandon Finnegan B. Finnegan	21	2014	World Series	KCR	2	0	1	.000	0	27.00	1	0	0	0	1.2	5	5	5	0	2	0	0	1	12	0	5.40	10.80	0.50	0.00	8.3	16.7	4.20	.556	27.00	27.00
15	Carlos Martinez C. Martinez	21	2013	World Series	STL	5	0	0		0	4.50	5	0	0	0	6.0	5	3	3	0	1	1	1	1	26	1	7.50	1.50	5.00	0.00	19.2	3.8	1.00	.263	4.50	7.50
16	Franklin Morales F. Morales	21	2007	World Series	COL	2	0	0		0	21.00	1	0	0	0	3.0	7	7	7	0	1	0	0	0	17	0	3.00	3.00	1.00	0.00	5.9	5.9	2.67	.467	21.00	21.00
17	Joel Zumaya J. Zumaya	21	2006	World Series	DET	3	0	1	.000	0	3.00	3	0	0	0	3.0	1	1	3	0	3	0	2	0	14	1	9.00	9.00	1.00	0.00	21.4	21.4	1.33	.125	9.00	3.00
18	Dontrelle Willis D. Willis	21	2003	World Series	FLA	3	0	0		0	0.00	3	0	0	0	3.2	4	0	0	0	2	0	0	0	17	0	7.36	4.91	1.50	0.00	17.6	11.8	1.64	.333	0.00	9.82
19	Mark Wohlers M. Wohlers	21	1991	World Series	ATL	3	0	0		0	0.00	1	0	0	0	1.2	2	0	0	0	2	0	0	0	9	0	5.40	10.80	0.50	0.00	11.1	22.2	2.40	.333	0.00	10.80
20	Tom Niedenfuer T. Niedenfuer	21	1981	World Series	LAD	2	0	0		0	0.00	0	0	0	0	5.0	3	0	2	0	1	0	0	1	20	0	0.00	1.80	0.00	0.00	0.0	5.0	0.80	.158	3.60	5.40
21	Bob Welch B. Welch	21	1978	World Series	LAD	3	0	1	.000	0	6.23	6	0	0	1	4.1	4	3	3	1	2	0	2	0	19	0	12.46	4.15	3.00	2.08	31.6	10.5	1.38	.300	6.23	8.31
22	Bruce Kison B. Kison	21	1971	World Series	PIT	2	1	0	1.000	0	0.00	3	0	0	0	6.1	1	0	0	0	2	3	0	0	24	0	4.26	2.84	1.50	0.00	12.5	8.3	0.47	.063	0.00	1.42
23	Jim Merritt J. Merritt	21	1965	World Series	MIN	2	0	0		0	2.70	1	0	0	0	3.1	2	1	1	0	0	0	0	0	11	0	2.70	0.00		0.00	9.1	0.0	0.60	.200	2.70	5.40
24	Jim Maloney J. Maloney	21	1961	World Series	CIN	1	0	0		0	27.00	1	0	0	0	0.2	4	2	2	0	1	0	0	0	7	0	13.50	13.50	1.00	0.00	14.3	14.3	7.50	.800	27.00	54.00
25	Juan Pizarro J. Pizarro	21	1958	World Series	MIL	1	0	0		0	5.40	3	0	0	0	1.2	2	1	1	0	1	0	0	0	8	1	16.20	5.40	3.00	0.00	37.5	12.5	1.80	.500	5.40	10.80