Francis might not even be the lineal champ depending on the full lineage. Many HW champs have been stripped
Forgive the copy/paste formatting mess, but this is the lineal champ history.
There are other paths, like if you count Harold Howard's "victory" over Royce instead of Sakuraba's, but they all lead to Ngannou being the current champ.
|11/12/1993|UFC 1|Royce Gracie|Gerard Gordeau|1|Submission (rear-naked choke)|10|
|5/1/2000|Pride Grand Prix 2000 Finals|Kazushi Sakuraba|Royce Gracie|1|TKO (corner stoppage)|0|
|5/1/2000|Pride Grand Prix 2000 Finals|Igor Vovchanchyn|Kazushi Sakuraba|1|TKO (corner stoppage)|0|
|5/1/2000|Pride Grand Prix 2000 Finals|Mark Coleman|Igor Vovchanchyn|1|TKO (submission to knees)|1|
|9/24/2001|PRIDE 16|Antônio Rodrigo Nogueira|Mark Coleman|1|Submission (triangle armbar)|6|
|3/16/2003|PRIDE 25|Fedor Emelianenko|Antônio Rodrigo Nogueira|1|Decision (unanimous)|19|
|6/26/2010|Strikeforce: Fedor vs. Werdum|Fabrício Werdum|Fedor Emelianenko|1|Submission (triangle armbar)|0|
|6/18/2011|Strikeforce: Overeem vs. Werdum|Alistair Overeem|Fabrício Werdum|1|Decision (unanimous)|1|
|2/2/2013|UFC 156|Antônio Silva|Alistair Overeem|1|KO (punches)|0|
|5/25/2013|UFC 160|Cain Velasquez|Antônio Silva|1|TKO (punches)|1|
|6/13/2015|UFC 188|Fabrício Werdum|Cain Velasquez|2|Submission (guillotine choke)|0|
|5/14/2016|UFC 198|Stipe Miocic|Fabrício Werdum|1|KO (punch)|3|
|7/7/2018|UFC 226|Daniel Cormier|Stipe Miocic|1|KO (punches)|1|
|8/17/2019|UFC 241|Stipe Miocic|Daniel Cormier|2|TKO (punches)|1|
|3/27/2021|UFC 260|Francis Ngannou|Stipe Miocic|1|KO (punch)|1+|