1. Novak Djokovic Reigns at all 4 Majors – Don’t expect to see this happen again.  It might happen again, but no male player had held all 4 major trophies simultaneously since 1969.  Steffi Graf held all 4 majors at the end of 1988 and after the 1989 Australian Open.  Serena Williams twice held all 4 majors for Serena Slams.  The Novak Slam was undervalued by the general sports media and by the tennis media. Laver won his clam on 2 surfaces and against a field much less deep than what tennis boasts today.  Until further notice, Novak holds the single greatest achievement in men’s tennis history (period).  
2. Serena Williams Ties Steffi Graf’s 22 Majors – Steffi Graf held the Open Era record for singles majors.  She now shares that record with Serena Williams.  Margaret Court’s overall record of 24 is under threat, but it is not yet broken.
3. Angelique Kerber Breaks Through and Wins 2 Majors – Kerber had a strong 2015 minus some early losses at the majors.  Kerber won the Australian and US Opens in 3 set championship thrillers.  She also was the Wimbledon runner-up and a Silver Medalist in Rio.  Kerber’s #1 ranking is well earned.
4. Andy Murray’s 2nd Wimbledon, 2nd Gold, and #1 Ranking – Andy Murray’s 2016 was extremely strong from Madrid to the end of the year  The Scot collected titles at Rome, Queen’s Club, Wimbledon, Rio, Beijing, Shanghai, the Bercy, and the London World Tour Finals plus runner-up finishes at Madrid, Roland Garros, and Cincinnati to claim the number one ranking.
5.  Monica Puig’s Golden Games –  Monica Puig was not expected to medal in Rio.  She produced incredible tennis and kept pulling upsets.  Her 3 set gold medal win over Angelique Kerber was one of the emotional highlights of the entire Rio Olympics. She won Puerto Rico’s first ever individual gold medal.  
6. Juan Martin del Potro’s Big Wins – JMDP upset Stan Wawrinka at Wimbledon.  This was not shocking given that Stan is not overly comfortable on grass.  JMDP upset Novak Djokovic and Rafael Nadal at the Rio olympics en route to a silver medal.  JMDP beat Andy Murray in the Davis Cup semifinal round and Marin Cilic from 2 sets down in the Davis Cup final.  His silver medal and Davis Cup titles brought Argentina a lot of joy.
7. Milos Raonic’s Upward Mobility – Milos is not afraid to tinker with his coaching team.  In 2016, he both brought in and parted ways with Carlos Moya and John McEnroe.  Milos won Brisbane by defeating Roger Federer.  He then lost a 5 set Australian Open semifinal clash to Andy Murray.  Milos reached the championship round at Queen’s Club again losing to Murray and lost in the Wimbledon final to Andy Murray.  At the season finale, Milos reached the semifinal round and held match point versus Andy Murray, but was again turned back by the Scot.  Still, Milos appears to be the first of his age group to be moving beyond being a potential threat to becoming an actual threat for big trophies.
8. Karolina Pliskova’s Cincinnati to New York Odyssey – Pliskova defeated Garbine Muguruza and Angelique Kerber consecutively to claim the Cincinnati crown.  Then in New York she beat both Venus and Serena Williams en route to the championship match. Angelique Kerber prevailed in 3 tight sets, but Pliskova’s successes in this stretch included wins over the players who claimed all 4 of 2016’s major titles.
9. Marin Cilic’s Cincinnati Celebration – What can you say?  He won the match and went a little nuts in a good way while looking like a human highlighter pen!  
    The celebration begins at the 3:10 mark
10. Dominic Thiem and Lucas Pouille’s Emergence – These two are good and can be good for tennis.

Honorable Mentions – Muguruza wins Roland Garros and Wawrinka added his 3rd slam in New York.  These stories are bigger than some on the list, but were not quite as engaging to me as the 10 ahead of them.