The Elisp manual section on Special Forms (10.2.7) lists around two dozen special forms, but two of them aren't special forms.
* `lambda', it turns out, is not a special form, but a macro that wraps itself in a call to the special form `function'. (The documentation for `lambda' refers to it as "self-quoting"; this might be better changed to "self-evaluating".)
* `track-mouse' isn't a special form, but a macro wrapper around the primitive function `internal--track-mouse', which isn't a special form either. (Section 29.15 on Mouse Tracking also inaccruately refers to `track-mouse' as a special form.)
On the other hand, the special form `inline' is not listed in the Special Forms section.
A list of all special forms can be gotten with
(let (special-forms)
(mapatoms
(lambda (sym)
(when (special-form-p sym)
(push sym special-forms))))
(sort special-forms #'string<))