There are the Irix 15mm 2.4 and 11mm F4
Samyang 24 1.4 20mm 1.8 14mm 2.8 12mm 2.8 fish eye and 24mm 3.5 tilt/shift
Legacy Pentax K: 15mm 3.5, 18mm 3.5, 20mm F4 24mm 2.8 and 3.5 and a 17mm F4 Fish eye
Pentax-m 20mm F4 (I have that one, it's nice)
Pentax-A: 16mm F3.5 15mm f2.8 Fish Eye 20mm F2.8 24mm F2.8
And then there are the AF FA* 24mm F2 and FA 20mm F2.8.
You can also look for the Sigma Super-Wide II 24mm F2.8 There is an AF and MF version.
The Sigma 15mm X DG 2.8 fish eye is still for sale and too many legacy Sigma wide angles for k-mount to
mention:
There must be something there for everybody until the 20 or 24mm F1.4 arrives (and there is a fish eye zoom coming too).