Please bear in mind that this is not a specific Doctor pattern, just a general doll wearing shoes, pants and a long-sleeved shirt or jumper. It will guide you with proportions, but you'll need to do a lot of customization if you want it to resemble any character. For example, if you want it to wear a jacket, you should decrease body to about 14 stitches once you reach the waist, so when you put on the (separately made) jacket he won't look like he's overweight.
One day, I might write a proper pattern for a specific Doctor or more - but for that I should make notes on the changes that I usually just make on a whim, so it's certainly not gonna be today...
Abbreviations (aka you need to know how to do):
ch - chain
st - stitch
sc - single crochet
sl st - slip stitch
BLO - back loop only
sc2tog - single crochet 2 together = single crochet decrease
dc2tog - double crochet 2 together = double crochet decrease
You can work in spirals if you prefer so, but at least for the legs I advise to work in joined rounds, it will be easier to connect them this way.
Start with making the legs. With shoe color, ch 5.
1. 2 sc in second ch from hook, sc in next 2 ch, 4 sc in last ch, then continue working on the other side of the foundation chain, to the last free loops of the chains: sc in next 2 ch, 2 sc in next ch, sl st to join to the first sc you made (12)
2. ch 1, working BLO sc in each st around, sl st to join (12)
3. ch 1, sc in next 3 st, sc2tog, dc2tog, sc2tog, sc in next 3 st, sl st to join (9)
4: ch 1, sc into each st around, sl st to join (9)
Switch to pants color:
5-9: ch 1, sc into each st around, sl st to join (9)
Finish off after row 9, and make the other leg the same way.
You can stuff legs with fiberfill, or if you want your doll to be more steady on his/her feet, you can use some kind of weighting material. I fill most of the legs with 4mm glass beads and put a little fiberfill on top so the beads won't spill out when I continue working.
Put the two legs together and find the innermost two stitches that are touching. Still using pants color, make a knot across these these two stitches, thus fixing the legs together, then chain 1.
1: Turn the legs so that the feet look away from you, and start to crochet - first on the left leg going around from rear to front, make a sc into each st (minus the one you used to tie the two legs together), then carry on on the other leg. You should end up with 16 stitches. Then sl st to join.
2: ch 1, sc in next 7 st, 2 sc in next st, sc in next 7 st, 2 sc in next st, sl st to join (18)
3: ch 1, sc in each st around, sl st to join (18)
Switch to shirt color.
4-9: ch 1, sc in each st around, sl st to join (18)
10: ch 1, [sc in next st, sc2tog] 6 times, sl st to join (12)
Stuff body.
11: ch 1, sc2tog 6 times (6)
Switch to skin color. You can continue working in joined rounds - I usually work in spiral from here on.
12: 2 sc in each st (12)
13: [sc in next st, 2 sc in next st] 6 times (18)
14: [sc in next st, 2 sc in next st, sc in next st] 6 times (24)
15-17: sc in each st (24)
18: [sc2tog, sc in next 2 st] 6 times (18)
19: [sc2tog, sc in next st] 6 times (12)
Stuff head.
20: sc2tog 6 times.
Finish off, use yarn end to close the tiny hole.
Arms:
Start with skin color.
1: 6 sc in magic ring
2: [sc in next st, 2 sc in next st] 3 times (9)
3: [sc in next st, sc2tog] 3 times (6)
Switch to shirt color
4-9: sc in each st (6)
Finish off leaving a long tail. Push only a small blob of fiberfill into hand, no need to stuff the rest of arm. Sew arms to body.
Ears (if necessary):
Make 3 sc in magic ring, finish off. Pull ring tight so the stitches form a half-circle.