33 annuals, irregularly numbered and published in tandem with both Fantastic Four (1st series) & Fantastic Four (3rd series).
Initially numbering: #1-27
#28: Fantastic Four / Fantastic 4 '98
#29: Fantastic Four 1999
#30: Fantastic Four 2000
#31: Fantastic Four 2001
Return: #32-33
There were subsequent Annual series, one in 2014 in conjunction with Fantastic Four (5th series) and a second in 2023 in conjunction with Fantastic Four (7th series).