Perfect games regular season: 20 since 1900.

Data from https://stathead.com/

All are 9 innings, i.e., not extra innings. Home team bold; pitcher home in 12 of 20.

Three of the most recent six were against Tampa. 

Rk	Player	Date	Tm	Opp	Rslt	App,Dec	IP	H	R	ER	BB	SO	HR	UER	Pit	Str	GSc	IR	IS	BF	AB	2B	3B	IBB	HBP	SH	SF	GDP	SB	CS	PO	BK	WP	ERA	WPA	RE24	aLI	DFS(DK)	DFS(FD)
1	Felix Hernandez	2012-08-15	SEA	TBR	W 1-0	SHO, W	9.0	0	0	0	0	12	0	0	113	77	99			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.712	4.097	1.071
2	Matt Cain	2012-06-13	SFG	HOU	W 10-0	SHO, W	9.0	0	0	0	0	14	0	0	125	86	101			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.124	3.808	.189
3	Philip Humber	2012-04-21	CHW	SEA	W 4-0	SHO, W	9.0	0	0	0	0	9	0	0	96	67	96			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.399	4.097	.600
4	Roy Halladay	2010-05-29	PHI	FLA	W 1-0	SHO, W	9.0	0	0	0	0	11	0	0	115	72	98			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.838	4.520	1.224
5	Dallas Braden	2010-05-09	OAK	TBR	W 4-0	SHO, W	9.0	0	0	0	0	6	0	0	109	77	93			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.339	4.430	.495
6	Mark Buehrle	2009-07-23	CHW	TBR	W 5-0	SHO, W	9.0	0	0	0	0	6	0	0	116	76	93			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.290	5.123	.406
7	Randy Johnson	2004-05-18	ARI	ATL	W 2-0	SHO, W	9.0	0	0	0	0	13	0	0	117	87	100			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.670	4.721	.964
8	David Cone	1999-07-18	NYY	MON	W 6-0	SHO, W	9.0	0	0	0	0	10	0	0	88	68	97			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.259	5.202	.363
9	David Wells	1998-05-17	NYY	MIN	W 4-0	SHO, W	9.0	0	0	0	0	11	0	0	120	79	98			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.477	4.944	.677
10	Kenny Rogers	1994-07-28	TEX	CAL	W 4-0	SHO, W	9.0	0	0	0	0	8	0	0	98	64	95			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.359	5.222	.499
11	Dennis Martinez	1991-07-28	MON	LAD	W 2-0	SHO, W	9.0	0	0	0	0	5	0	0	96	66	92			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.574	4.037	.866
12	Tom Browning	1988-09-16	CIN	LAD	W 1-0	SHO, W	9.0	0	0	0	0	7	0	0	101	72	94			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.694	4.016	1.050
13	Mike Witt	1984-09-30	CAL	TEX	W 1-0	SHO, W	9.0	0	0	0	0	10	0	0			97			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.812	4.581	1.181
14	Len Barker	1981-05-15	CLE	TOR	W 3-0	SHO, W	9.0	0	0	0	0	11	0	0			98			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.474	4.046	.714
15	Catfish Hunter	1968-05-08	OAK	MIN	W 4-0	SHO, W	9.0	0	0	0	0	11	0	0			98			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.489	3.209	.793
16	Sandy Koufax	1965-09-09	LAD	CHC	W 1-0	SHO, W	9.0	0	0	0	0	14	0	0	113	79	101			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.674	3.749	1.044
17	Jim Bunning	1964-06-21 (1)	PHI	NYM	W 6-0	SHO, W	9.0	0	0	0	0	10	0	0	89	68	97			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.293	3.877	.447
18	Charlie Robertson	1922-04-30	CHW	DET	W 2-0	SHO, W	9.0	0	0	0	0	6	0	0			93			27	27	0	0	0	0	0	0	0	0	0	0	0	0	0.00	0.633	4.641	.917
19	Addie Joss	1908-10-02	CLE	CHW	W 1-0	SHO, W	9.0	0	0	0	0	3	0	0			90			27	27	0	0		0	0						0	0	0.00
20	Cy Young	1904-05-05	BOS	PHA	W 3-0	SHO, W	9.0	0	0	0	0	8	0	0			95			27	27	0	0		0	0						0	0	0.00

In the first six the opposing pitcher batted.

Designated Hitter (DH) in lineup against 9 of 20 (9 of most recent 14):
1981 Barker
1984 Witt
1994 Rogers
1998 Wells
1999 Cone
2009 Buehrle
2010 Braden
2012 Humber
2012 Hernandez.

The only years with more than one:

2012: 3

2010: 2

Of the most recent ten, only two were against teams that existed before 1961:

Randy Johnson 2004 against Boston/Milwaukee/Atlanta Braves

David Wells 1998 against Minnesota Twins (Washington Senators).

Most SO: 14 by Koufax and Cain. Fewest SO since 1964: 5 by Dennis Martinez.

Most common scores:

1-0 six times

4-0 five times.

Least common scores, once each: 10-0 and 5-0.

14 of the 20 games have number of pitches; 9 of 14 at least 100.

Most pitches: Cain 125 in 2012

Fewest pitches:

Cone 88
Bunning 89
Martinez 96
Humber 96

Rogers 98.

Don Larsen: greatest single game performance in World Series history, passes away. Thursday, January 2, 2020

Sandy Koufax perfect game: two Cubs batters making MLB debut. Thursday, November 5, 2020