I mentioned this in the comments to the recap of Kris Bryant's career-best game, but thought you'd all like to see the entire list of Cubs who have homered three times in a game. This table is sorted in alphabetical order by last name. For some reason the column headings don't post here, but you should be able to figure them out. The last column is the number of homers.
|1||Moises Alou||2003-07-04||CHC||STL||L 8-11||5||5||3||3||0||0||3|
|2||Ernie Banks||1957-09-14 (2)||CHC||PIT||W 7-3||4||3||4||3||0||0||3|
|3||Ernie Banks||1963-06-09||CHC||LAD||L 8-11||5||5||3||3||0||0||3|
|4||Ernie Banks||1955-08-04||CHC||PIT||W 11-10||5||4||4||0||0||3|
|5||Ernie Banks||1962-05-29||CHC||MLN||L 9-11||5||5||3||4||1||0||3|
|6||Brant Brown||1998-06-18||CHC||PHI||W 12-5||5||5||3||4||0||0||3|
|7||Kris Bryant||2016-06-27||CHC||CIN||W 11-8||5||5||4||5||2||0||3|
|8||Andre Dawson||1987-08-01||CHC||PHI||W 5-3||4||4||3||3||0||0||3|
|9||Babe Herman||1933-07-20||CHC||PHI||W 10-1||5||5||3||4||0||0||3|
|10||Rogers Hornsby||1931-04-24||CHC||PIT||W 10-6||5||5||3||4||0||0||3|
|11||Dave Kingman||1978-05-14||CHC||LAD||W 10-7||8||7||3||4||0||0||3|
|12||Dave Kingman||1979-07-28||CHC||NYM||L 4-6||4||4||3||4||0||0||3|
|13||Dave Kingman||1979-05-17||CHC||PHI||L 22-23||7||6||4||3||0||0||3|
|14||Hank Leiber||1939-07-04 (1)||CHC||STL||L 4-6||4||3||3||0||0||3|
|15||Clyde McCullough||1942-07-26 (1)||CHC||PHI||L 3-4||4||4||3||3||0||0||3|
|16||George Mitterwald||1974-04-17||CHC||PIT||W 18-9||5||4||3||4||1||0||3|
|17||Rick Monday||1972-05-16||CHC||PHI||W 8-1||5||5||3||4||0||0||3|
|18||Walt Moryn||1958-05-30 (2)||CHC||LAD||W 10-8||5||5||3||3||0||0||3|
|19||Dioner Navarro||2013-05-29||CHC||CHW||W 9-3||4||3||4||3||0||0||3|
|20||Bill Nicholson||1944-07-23 (1)||CHC||NYG||W 7-4||3||4||3||0||0||3|
|21||Andy Pafko||1950-08-02 (2)||CHC||NYG||L 6-8||4||3||3||3||0||0||3|
|22||Adolfo Phillips||1967-06-11 (2)||CHC||NYM||W 18-10||5||5||4||4||0||0||3|
|23||Aramis Ramirez||2004-07-30||CHC||PHI||W 10-7||4||4||3||3||0||0||3|
|24||Aramis Ramirez||2010-07-20||CHC||HOU||W 14-7||5||5||3||3||0||0||3|
|25||Aramis Ramirez||2004-09-16||CHC||CIN||W 5-4||5||5||3||4||1||0||3|
|26||Tuffy Rhodes||1994-04-04||CHC||NYM||L 8-12||5||4||3||4||0||0||3|
|27||Hank Sauer||1952-06-11||CHC||PHI||W 3-2||4||4||3||3||0||0||3|
|28||Hank Sauer||1950-08-28 (1)||CHC||PHI||W 7-5||4||3||3||3||0||0||3|
|29||Alfonso Soriano||2007-06-08||CHC||ATL||W 9-1||6||5||3||4||0||0||3|
|30||Alfonso Soriano||2008-09-06||CHC||CIN||W 14-9||5||5||4||4||0||0||3|
|31||Sammy Sosa||2002-08-10||CHC||COL||W 15-1||4||4||3||3||0||0||3|
|32||Sammy Sosa||1998-06-15||CHC||MIL||W 6-5||4||4||3||3||0||0||3|
|33||Sammy Sosa||2001-08-09||CHC||COL||L 5-14||4||4||3||3||0||0||3|
|34||Sammy Sosa||2001-09-23||CHC||HOU||L 6-7||4||4||3||3||0||0||3|
|35||Sammy Sosa||1996-06-05||CHC||PHI||W 9-6||4||4||3||3||0||0||3|
|36||Sammy Sosa||2001-08-22||CHC||MIL||W 16-3||5||4||3||3||0||0||3|
|37||Lee Walls||1958-04-24||CHC||LAD||W 15-2||6||6||3||3||0||0||3|
|38||Billy Williams||1968-09-10||CHC||NYM||W 8-1||4||4||3||3||0||0||3|
|39||Hack Wilson||1930-07-26||CHC||PHI||W 16-2||6||5||4||3||0||0||3|
As you can see, it's happened just 39 times in Cubs history (since 1913, and given the very small number of home runs hit prior to that, it's not likely we're missing many, or any). The first one was Hack Wilson's in 1930.
Six Cubs have done this more than once:
Sammy Sosa, 6 Ernie Banks, 5 Aramis Ramirez, 3 Dave Kingman, 3 Alfonso Soriano, 2 Hank Sauer, 2
The six three-run homer games by Sosa is the major-league record, tied with Johnny Mize, a New York Giant who did it in the 1930s and 1940s.
Sauer, nearly forgotten today, was a popular Cub for seven seasons in the 1950s who was named National League MVP in 1952; he led the league in homers and RBI that year and it was the Cubs' only non-losing season between 1946 and 1963. Sauer's 198 homers as a Cub still rank ninth on the all-time team list.
There are some odd names on that list, such as Dioner Navarro (the last Cub to do it before Bryant), Tuffy Rhodes (who did it on Opening Day 1994, then hit only five more the rest of that season, and the Cubs lost the game 12-8 despite the three homers), Clyde McCullough (who had only two other home runs the year he did it, 1942), and George Mitterwald, who by legend was supposedly told he wasn't going to play that day, went out on a bender, came into the ballpark finding out he was needed to play, and had his three-homer game nursing a hangover. I was at that game, April 17, 1974, a warm, very windy day where the Cubs won 18-9. Mitterwald hit only four more homers the rest of the 1974 season.
The Cubs' record is 28-11 when a player hits three homers in a game -- somehow, you might think it'd be better.
Such is baseball history.
There's also this team record that Bryant set Monday night:
Youngest #Cubs to hit 3 HR in game— Christopher Kamka (@ckamka) June 28, 2016
24 y, 175 d Kris Bryant (6/27/2016)
24 y, 185 d Ernie Banks (8/4/1955)
25 y, 108 d Lee Walls (4/24/1958)
It was Bryant's first three-homer game. It almost certainly won't be his last.